Toner, two-component developer, and image forming method

ABSTRACT

A toner of the present invention is a toner comprising an additive and a toner matrix that contains a binder resin, a colorant, and a wax, in which the additive contains an inorganic micropowder to whose surface polysiloxane and at least one selected from fatty acids and derivatives thereof are adhered. Thus, the present invention provides the toner, a two-component developer, and an image forming method with which oil-less fixing is possible without the use of an oil on a fixing roller. Furthermore, the present invention provides the two-component developer that causes less carrier deterioration by toner-spent even when used in combination with a toner containing wax or another such release agent and thus the developer has good durability. In addition, the present invention provides the toner, the two-component developer, and the image forming method with which partial transfer defects are reduced and high transfer efficiency can be obtained.

TECHNICAL FIELD

The present invention relates to a two-component developer and an imageformation device used in copiers, laser printers, plain paper faxmachines, color PPCs, color laser printers, color fax machines, andapparatuses that combine these functions.

BACKGROUND ART

Electrophotographic apparatuses in recent years have been shifting fromoffice use to personal use, and this has been accompanied by a need forthese apparatuses to be smaller and faster, to provide higher imagequality, to be maintenance-free, and so on. Accordingly, some of therequirements these apparatuses now must meet include use of acleaner-less process in which waste toner is recovered in development,without having to clean away waste toner left behind after transfer; theuse of a tandem color process with which color images can be output at ahigh speed; oil-less fixing with which a sharp color image having highgloss and high optical transmissivity can be obtained with no offseteven without the use of a fixing oil for preventing offset duringfixing; easy maintenance; and low ozone emission. All of these functionsmust be realized at the same time, and improving toner characteristics,and not only the process, is an important factor.

With a color printer, an image support (hereinafter referred to as aphotosensitive member) is charged by corona discharge, using a charger,after which the photosensitive member is irradiated with various colorsof latent image in the form of optical signals, thereby forming anelectrostatic latent image. This is developed with a first color (suchas yellow) toner to visualize the latent image. After this, a transfermember that has been charged to the opposite polarity of the charge ofthe yellow toner is brought into contact with the photosensitive member,which transfers the yellow toner image formed on the photosensitivemember. The photosensitive member is destaticized after cleaning awayany toner remaining behind from transfer, which concludes thedevelopment and transfer of the first color toner. Then, for other tonercolors such as magenta and cyan, the same operation as for yellow toneris repeated, which builds up toner images of various colors on thetransfer member and forms a color image. These superimposed toner imagesthen are transferred onto a paper that has been charged to the oppositepolarity from that of the toner, and this constitutes a four-pass colorprocess.

There also has been a proposal for a tandem color process in which aprimary transfer process first is executed by disposing in a row aplurality of image formation stations having a charger, a photosensitivemember, a developing unit, and so forth, and bringing an endlesstransfer member into contact with the photosensitive member tocontinuously transfer consecutive colors of toner to the transfermember, so that a multilayer transferred color toner image is formed onthe transfer member, and then a secondary transfer process is executedby transferring the multilayer toner image formed on the transfer memberall at once to a transfer medium such as a paper or an overheadprojector (OHP) sheet, as well as a proposal for a tandem color processinvolving direct and successive transfer to the paper, OHP sheet, orother transfer medium, without using a transfer member.

In the fixing process, with a color image, the color toner must bemelted to mix the colors and increase optical transmissivity. If thetoner does not melt sufficiently, light is scattered on the surface orin the interior of the toner image, resulting in a loss of the originalcolor tone of the toner dye and preventing the light from reaching lowerlayers in overlapping portions, which decreases color reproducibility.Therefore, one of the conditions required for a toner is that it becapable of completely melting and have enough optical transmissivitythat does not impair color tone. The need for OHP sheets to have goodoptical transmissivity has increased as color presentations have becomemore commonplace. When a color image is obtained, offset occurs whentoner adheres to the surface of the fixing roller, so that the fixingroller has to be coated with a large quantity of oil or the like, whichcomplicates handling and the apparatus configuration. Consequently,there is a need for oil-less fixing, in which no oil is used duringfixing (discussed below), in order to make apparatuses smaller, easierto maintain, and less expensive. A design in which a wax or other suchrelease agent is added to a binder resin having sharp meltingcharacteristics is starting to be put to use in an effort to accomplishthis goal.

However, a problem with a toner such as this is that the toner has theproperty of being highly cohesive, so that toner image disruption duringtransfer and the tendency toward poor transfer are likely to be morepronounced, making it difficult to achieve both good transfer and goodfixing. Also, in the course of two-component development, toner-spenttends to occur, in which the low-melting point component of the toneradheres to the carrier surface as a result of heat generated bymechanical impact and friction, such as impact and friction betweenparticles, or impact and friction between particles and the developingunit. This diminishes the ability of the carrier to be charged, andshortens the service life of the developer. In an effort to provide acoated carrier having an extended-life, it has been proposed, forexample, in Patent Document 1 (see below) that the surface of a carriercore be coated with a resin of a copolymer of a nitrogen-containingfluoroalkyl (meth)acrylate and a vinyl monomer, a copolymer of afluoroalkyl (meth)acrylate and a nitrogen-containing vinyl monomer, orthe like. It is stated in these documents that a coated carrier with arelatively long service life can be obtained by coating the carrier coresurface with a solvent-soluble fluorine-containing polymer having imidebonds, or a copolymer of a nitrogen-containing monomer and a fluorinatedmonomer. Nevertheless, the resin adhesive strength is low at theadhesive boundary with the carrier, and the strength of the resin is toolow, so that adequate impact resistance has yet to be obtained. Also,the chargeability of fluorine makes it difficult to negatively chargethe toner, so that an adequate charge cannot be imparted to the toner,resulting in image fogging, uneven density, and other such problems.

Patent Document 2, for example, proposes a carrier coated with asilicone resin containing an aminosilane coupling agent in combinationwith a toner of specific components in an effort to improve thedurability of a developer by preventing a decrease in toner charge inatmospheres of high humidity, but these approaches were inadequate interms of preventing toner-spent.

Patent Document 3 proposes a carrier in which fluorine-substituted alkylgroups have been introduced into the silicone resin of a coating layer,as opposed to positively-chargeable toner. Patent Document 4 proposes acoated carrier containing conductive carbon and a crosslinkedfluorine-modified silicone resin, which affords better developingperformance in a high speed process, and this performance does notdeteriorate over an extended period. This takes advantage of theexcellent charging characteristics of a silicone resin, and thefluorine-substituted alkyl groups impart lubricity, partability, waterrepellency, and other such benefits, make wear, separation, cracking,and the like less likely to occur, and prevent toner-spent. However, notonly is the effect unsatisfactory in terms of wear, separation,cracking, and the like, but while suitable charging is obtained with apositively-chargeable toner, when a negatively-chargeable toner is used,the amount of charge is too low, oppositely chargeable toner(positively-chargeable toner) is generated in large quantity, fogging,toner scattering, and other such problems occur, and the product cannotstand up to actual use.

A variety of toner compositions also have been proposed. As is wellknown, a toner for electrostatic charge development used inelectrophotography generally includes a resin component (binder resin),a coloration component composed of a pigment or dye, a plasticizer, acharge control agent, and any necessary additives such as a releaseagent. A natural or synthetic resin is used, either singly or as asuitable mixture, as the resin component.

The above-mentioned additives are pre-mixed in an appropriate ratio, themixture is heated and kneaded by thermal melting, and finely pulverizedwith an air stream collision board, and the resulting fine powder isgraded to complete a toner matrix. Chemical polymerization such asemulsion aggregation or suspension polymerization is another way toproduce a toner matrix. After this, an additive such as hydrophobicsilica is added to the toner matrix to complete the toner. Toner aloneis used in single-component development, while a two-component developeris obtained by mixing toner with a carrier composed of magneticparticles.

Patent Document 5 discloses the constitution in which TiO₂ whose surfaceis coated with a compound with a melting point of 40 to 150° C., such asa C₁₃ to C₃₉ saturated fatty acid, a fatty acid ester, or a aliphaticalcohol having at least 15 carbon atoms, is added, and provides a tonerwhose fluidity and anti-caking properties are improved, and in whichcleaning defects hardly occur.

Patent Document 6 discloses a toner containing titanium oxide treatedwith a fatty acid metal salt (A), and a carrier comprising ferriteparticles covered with fluorine resin (B), and provides the effect ofenhancing charging stability of the developer and speeding up the startof charging after a new toner is supplied.

Patent Document 7 discloses resin microparticles that have an averageparticle size of 0.03 to 2.0 μm and whose surfaces have been treatedwith a fatty acid or a fatty acid derivative, and discloses the effectof obtaining images that are faithful to latent images regardless of thecondition of the transfer material, and, in particular, high qualityimages without partial transfer defects.

Patent Document 8 discloses a toner containing inorganic micropowdersubjected to treatment for imparting hydrophobic property throughhydrolysis of a fatty acid compound in an aquatic system and inorganicmicropowder subjected to treatment for imparting hydrophobic propertywith silicone oil in an aquatic system, and provides a color toner thatis affected less by temperature and humidity, has a stable frictionchargeability, and is excellent in producing sharp images withoutfogging and in durability.

Patent Document 9 discloses a constitution in which magnetic particleswhose surfaces have been treated with a fatty acid, a fatty acid metalsalt, or a fatty acid ester are added to a polyester resin, in order toobtain a positively-chargeable magnetic toner having a stable imagequality even under the condition of high humidity and high temperature.

Patent Document 10 discloses a constitution in which an inorganiccompound whose surface has been treated with at least one treatmentagent selected from the group consisting of fatty acid metal salts andC₂₀ to C₆₀ alcohols being solid at room temperature is added, andproposes a dry toner for electrostatic charge development that has goodfluidity, good cleaning property, excellent environmental stability anddurability, and does not cause toner filming on the surface of aphotosensitive member, the surface of a carrier used in two-componentdevelopment, or the surface of a charge imparting member used inone-component development.

Patent Document 11 discloses a constitution in which microparticles withcore microparticles coated with a long chain fatty acid metal salt areadded to the surface of toner particles. This constitution providesimages that have good transfer and do not cause partial transfer defectsin characters, while maintaining the image density.

Patent Document 12 discloses a magnetic toner containing hydrophobicsilica and a superfine particle titanium oxide powder that is madehydrophobic by surface treatment with a fatty acid salt of aluminum, andprovides a magnetic toner having a stable image quality for a longperiod of time without causing filming on the surface of aphotosensitive member.

However, merely adding inorganic microparticles whose surfaces aretreated with, for example, a fatty acid does not provide sufficientenvironmental characteristics, and the treatment amount is limited sothat a sufficient charging stability and parting effect cannot beobtained, although the effect is achieved to a certain extent.Furthermore, a constitution in which a large amount of low-melting pointwax is blended in a toner for oil-less fixing is not sufficient tomaintain good fluidity or to stabilize the quality of developed images.

In Patent Document 13, a non-free fatty acid type of carnauba wax and/ora montan-based ester wax and an oxidized rice wax with an acid value of10 to 30 are used as a wax serving as a release agent, while a vinylcopolymer having a melting point of 85 to 100° C. that is polymerized inthe presence of a natural gas-based Fischer-Tropsch wax is used inPatent Document 14, and Patent Document 15 discloses that a polyhydricalcohol component is polycondensed with a dicarboxylic acid and atrivalent or higher carboxylic acid compound, the average dispersedparticle size of the release agent is from 0.1 to 3 μm, the particlesize of the additive is from 4 to 200 nm, and the addition is made in anamount of 1 to 5 parts by weight. Patent Document 16 discloses thatfixability is enhanced by including a fluorine-modified polyolefin resinsuch as polypropylene that has been modified with an organofluorinecompound such as perfluoro-octyl methacrylate. In Patent Document 17, itis stated that a toner with excellent fixability, offset resistance, andoptical transmissivity can be obtained by using a product obtained froma synthetic hydrocarbon wax and an unsaturated polyvalentalkylcarboxylic acid and an alkyl alcohol or amine. In Patent Document18, it is disclosed that offset resistance during fixing is improved byblending a low-molecular weight polyolefin containing fluorine andhaving a softening point of 80 to 140° C., which is a molten mixture ofpolytetrafluoroethylene and a low-molecular weight olefin, and it isstated that this is effective at improving fixability.

The purpose of adding a low-melting point release agent such aspolyethylene or polypropylene wax to a resin composition obtained byblending or copolymerizing these high and low molecular weightcomponents is to improve parting from a heat roller during fixing, andthereby increase offset resistance. However, it is difficult to increasethe dispersibility of these release agents in a binder resin, oppositelychargeable toner tends to be generated, and fogging occurs in thenon-image portions. Filming also tends to occur on the photosensitivemember.

A particular problem is the phenomenon whereby the surface of thecarrier, which is the toner transport and charging member, iscontaminated in the course of using as a two-component developer a tonerto which one of these release agents has been added (calledtoner-spent). Accordingly, there is a decrease in chargeability, as wellas a drop in toner transport performance. Furthermore, carrier adhesiontends to be caused, which causes damage to the intermediate transfermember. Therefore, currently the carrier is replaced and discarded afterbeing used for a certain length of time, which drives up the runningcosts.

Patent Document 1: JP S61-80161A

Patent Document 2: Japanese Patent No. 2,619,439

Patent Document 3: Japanese Patent No. 2,801,507

Patent Document 4: JP 2002-23429 A

Patent Document 5: JP S63-174068 A

Patent document 6: JP H04-452 A

Patent document 7: JP H04-274443A

Patent document 8: JP H05-34984A

Patent document 9: JP H05-72802A

Patent document 10: JP H05-165250A

Patent document 11: JP H05-241367A

Patent document 12: JP H10-161340A

Patent document 13: JP H02-266372A

Patent document 14: JP H09-281748A

Patent document 15: JP2000-214638A

Patent document 16: JP H05-333584A

Patent document 17: JP 2000-10338A

Patent document 18: JP H05-188632A

DISCLOSURE OF INVENTION

In order to achieve an oil-less fixing toner with which no oil is usedon a fixing roller, the present invention provides a toner, atwo-component developer, and an image forming method with which oil-lessfixing is possible by using a release agent such as wax in the toner.Furthermore, the present invention provides the two-component developerthat causes less carrier deterioration by toner-spent even when used incombination with a toner containing wax or another such release agentand that has good durability. In addition, the present inventionprovides the toner, the two-component developer, and the image formingmethod with which partial transfer defects are reduced and high transferefficiency can be obtained.

A toner of the present invention is a toner comprising an additive and atoner matrix that includes a binder resin, a colorant, and a wax, inwhich the additive contains an inorganic micropowder to whose surfacepolysiloxane and at least one selected from fatty acids and derivativesthereof are adhered.

Next, a two-component developer of the present invention is atwo-component developer comprising a carrier and a toner containing anadditive and a toner matrix that contains at least a binder resin, acolorant and a wax, in which the additive contains an inorganicmicropowder whose surface is treated with polysiloxane and at least oneselected from fatty acids and derivatives thereof, and in which thecarrier comprises a core material whose surface is coated with a resincontaining a fluorine-modified silicone resin containing an aminosilanecoupling agent.

Next, a first image forming method of the present invention is an imageforming method making use of a developing means in which an AC bias witha frequency of 5 to 10 kHz and a bias of 1.0 to 2.5 kV (p-p) is appliedalong with a DC bias between a photosensitive member and a developingroller, and a peripheral speed ratio between the photosensitive memberand the developing roller is from 1:1.2 to 1:2, in which the method usesa toner containing an additive and a toner matrix that contains at leasta binder resin, a colorant, and a wax, and the additive contains aninorganic micropowder to whose surface polysiloxane and at least oneselected from fatty acids and derivatives thereof are adhered.

Next, a second image forming method of the present invention makes useof a transfer system in which there are a plurality of toner imageforming stations including at least an image support, charging means forforming an electrostatic latent image on the image support, and a tonersupport. The electrostatic latent image having been formed on the imagesupport is visualized by a toner containing an additive and a tonermatrix that contains at least a binder resin, a colorant, and a wax, theadditive containing an inorganic micropowder to whose surfacepolysiloxane and at least one selected from fatty acids and derivativesthereof are adhered. A primary transfer process in which the toner imagehaving been obtained by visualizing the electrostatic latent image istransferred to an endless transfer member by bringing the transfermember into contact with the image support, is executed sequentially andcontinuously to form a multilayer transferred toner image on thetransfer member, and then a secondary transfer process in which themultilayer toner image having been formed on the transfer member istransferred all at once to a transfer medium, is executed. The transferprocesses satisfy d1/v≦0.65 (sec), when d1 (mm) is a distance from afirst primary transfer position to a second primary transfer position,or a distance from the second primary transfer position to a thirdprimary transfer position, or a distance from the third primary transferposition to a fourth primary transfer position, and v (mm/s) is theperipheral speed of the photosensitive member.

Next, a third image forming method of the present invention makes use ofa transfer system in which there are a plurality of toner image formingstations including at least an image support, charging means for formingan electrostatic latent image on the image support, and a toner support.The electrostatic latent image having been formed on the image supportis visualized by a toner containing an additive and a toner matrix thatcontains at least a binder resin, a colorant, and a wax, the additivecontaining an inorganic micropowder to whose surface polysiloxane and atleast one selected from fatty acids and derivatives thereof are adhered,a transfer process in which the toner image having been obtained byvisualizing the electrostatic latent image is transferred to a transfermedium sequentially and continuously, is executed. The transferprocesses satisfy d1/v≦0.65 (sec), when d1 (mm) is a distance from afirst primary transfer position to a second primary transfer position,or a distance from the second primary transfer position to a thirdprimary transfer position, or a distance from the third primary transferposition to a fourth primary transfer position, and v (mm/s) is theperipheral speed of the photosensitive member.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view showing the configuration of an imageformation device used in a working example of the present invention.

FIG. 2 is a cross-sectional view showing the configuration of a fixingunit used in a working example of the present invention.

FIG. 3 is a simplified diagram of a toner kneading device used in aworking example of the present invention.

FIG. 4 is a plan view of a toner kneading device used in a workingexample of the present invention.

FIG. 5 is a side view of a toner kneading device used in a workingexample of the present invention.

FIG. 6 is a cross-sectional view of a toner kneading device used in aworking example of the present invention.

FIG. 7 is a diagram of the constitution of a toner pulverization processused in a working example of the present invention.

FIG. 8 is a cross-sectional view along the line I-I′ in FIG. 7.

FIG. 9 is a detailed view of the location B in FIG. 8

1: photosensitive member, 2: charging roller, 3: laser signal light, 4:developing roller, 5: blade, 10: first transfer roller, 12: transferbelt, 14: second transfer roller, 13: drive tensioning roller, 17:transfer belt unit, 18B, 18C, 18M, and 18Y: image formation units, 18:image formation unit group, 201: fixing roller, 202: press roller, 203:fixing belt, 205: induction heater, 206: ferrite core, 207: coil, 508:metering supply unit, 500: pulverizer, 501: rotor, 502: stator, 503: rawmaterial, 506: jagged component, 509: cooling unit, 511: air, 512:thermometer, 514: bag filter, 515: cyclone, 516: airflow meter, 517:blower, 518: inorganic micropowder supply device, 519: vibrator, 602:roll (RL1), 603: roll (RL2), 604: molten toner film wound onto roll(RL1), 605: inlet for heating medium, 606: outlet for heating medium

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention affords good digital image quality and moreprecise color reproduction, allows both optical transmissivity andoffset resistance to be achieved, without the use of an oil forpreventing offset on the fixing roller, and extends the service life bypreventing toner-spent caused by the toner component on the carrier intwo-component development.

(1) Additives

The additive in this embodiment is an externally added micropowdertreated with a fatty acid or the like, which results in excellentpartability between the photosensitive member and any toner adhering tothe photosensitive member. Furthermore, a treatment that involvescombination with polysiloxane makes the toner charge distribution moreuniform, which results in fewer partial transfer defects and preventsback-transfer. As a result, partial transfer defects and back-transfercan be prevented even with a toner that has become more cohesive throughthe addition of a certain amount of wax for the sake of oil-less fixing.Also, when used in combination with the carrier or wax (discussedbelow), this results in excellent partability, toner-spent resistancecan be further enhanced by the better uniformity in toner chargedistribution resulting from treatment with polysiloxane, handling withinthe developing unit is facilitated, and the uniformity of toner densityis increased. The occurrence of developing memory also can besuppressed. Furthermore, filming of toner components on thephotosensitive member can be prevented and fusion of toner components tothe fixing and heating member can be prevented. Also, both good transferand oil-less fixing can be achieved even with a toner of smallerparticle size. Latent images can be reproduced more faithfully indevelopment. Also, transfer can be performed without decreasing thetransfer efficiency of the toner particles. Further, retransfer can beprevented in tandem transfer, and the occurrence of partial transferdefects can be suppressed. In addition, a high image density can beobtained even when the amount of developer is decreased.

Examples of additives in this embodiment include metal oxidemicropowders such as silica, alumina, titanium oxide, zirconia,magnesia, ferrite, and magnetite, titanates such as barium titanate,calcium titanate, and strontium titanate, zirconates such as bariumzirconate, calcium zirconate, and strontium zirconate, and mixtures ofthese. Of fatty acids, fatty acid esters, fatty acid amides, and fattyacid metal salts that are used for the surface treatment of an inorganicmicropowder, examples of the fatty acids and the fatty acid metal saltsinclude caprylic acid, capric acid, undecylic acid, lauric acid,myristic acid, palmitic acid, stearic acid, behenic acid, montanic acid,lacceric acid, oleic acid, erucic acid, sorbic acid, and linoleic acid.Of these, a fatty acid having 15 to 20 carbon atoms is preferred.

Examples of the metal that constitutes the fatty acid metal salt includealuminum, zinc, calcium, magnesium, lithium, sodium, lead, and barium.Of these, aluminum, zinc, and sodium are preferred. Particularlypreferable are difatty acids aluminum such as aluminum distearate(Al(OH)(C₁₇H₃₅COO)₂) and monofatty acid aluminum such as aluminummonostearate (Al(OH)₂(C₁₇H₃₅COO)). Having OH groups prevents excesscharging and keeps transfer defects to a minimum. This also seems toimprove treatability with silica and other such inorganic micropowdersduring treatment.

Preferable examples of an aliphatic amide include a C₁₆ to C₂₄ saturatedor monounsaturated aliphatic amide such as palmitic acid amide,palmitoleic acid amide, stearic acid amide, oleic acid amide, arachidicacid amide, eicosenoic acid amide, behenic acid amide, erucic acidamide, and lignoceric acid amide.

Preferable examples of fatty acid esters include methyl, ethyl, butyl,glycerol, pentaerythritol, polypropylene glycol, trimethylolpropaneesters. A fatty acid pentaerythritol monoester, a fatty acidpentaerythritol triester, a fatty acid trimethylol propane ester, or thelike is particularly preferable.

A hydroxystearic acid derivative, a glycerol fatty acid ester, a glycolfatty acid ester, a sorbitan fatty acid ester, or another suchpolyhydric alcohol fatty acid ester is the preferred material, and thesecan be used singly or in combinations of two or more types.

Preferable examples of polysiloxane include polysiloxane selected fromdimethylpolysiloxane, diphenyl polysiloxane, and methylphenylpolysiloxane. Also, polysiloxane selected from phenyl hydrogenpolysiloxane, methyl hydrogen polysiloxane, and phenyl hydrogen methylhydrogen polysiloxane is used prefeferably.

The surface treatment is performed by dissolving the above polysiloxaneand fatty acid in a hydrocarbonate organic solvent such as toluene,xylene, hexane, or isoper, wet mixing this solution along with silica,titanium oxide, alumina, or another such micropowder in a disperser,causing the polysiloxane or fatty acid to adhere to the surface of themicropowder by using a treatment agent, and thereby effecting a surfacetreatment, after which this product is dried and the solvent is removed.

In this case, the mixing ratio between the fatty acid or the like andthe polysiloxane preferably is 2:1 to 1:20. If a fatty acid or the likeis contained at more than a ratio of 2:1, the charge amount of silicabecomes high, and thus image density is lowered and charge-up occursmore easily in the case of two-component development. If a fatty acidmetal salt or the like is contained at less than a ratio of 1:20,particle transfer defects, a decrease in the effect on back-transfer,and an increase in toner-spent on the carrier are caused.

In a preferred embodiment, the surface of an inorganic micropowder thatis to be treated is treated with a coupling agent and/or polysiloxane,and then treated with a fatty acid or the like and polysiloxane. This isbecause a more uniform treatment is possible than when hydrophilicsilica is treated merely with a fatty acid, and a higher toner charge isattained, and fluidity is higher when the powder is added to the toner.

In another preferred embodiment, the surface of an inorganic micropowderthat is to be treated is treated with polysiloxane, and then treatedwith a fatty acid or the like. This is because the treatment amount ofthe fatty acid or the like can be reduced. Furthermore, a more uniformtreatment is possible, and a higher toner charge is attained andfluidity is higher when the powder is added to the toner.

Examples of silane coupling agents include dimethyldichlorosilane,trimethylchlorosilane, allyldimethylchlorosilane, hexamethyldisilazane,allylphenyldichlorosilane, benzylmethylchlorosilane,vinyltriethoxysilane, gamma-methacryloxypropyltrimethoxysilane,vinyltriacetoxysilane, divinylchlorosilane, anddimethylvinylchlorosilane. The silane coupling agent treatment involves,for example, a dry treatment in which the micropowder is stirred and putinto a cloud state, and this is reacted with a vaporized silane couplingagent, or a wet treatment in which a silane coupling agent dispersed ina solvent is drip-reacted with a micropowder.

It is preferable for an inorganic micropowder with an average particlesize of 6 nm to 200 nm to be added externally in an amount of 1.0 to 5.5parts by weight per 100 parts by weight of a toner matrix. If the amountis under 1.0 parts by weight, toner fluidity tends to decrease andback-transfer cannot be completely eliminated during transfer. If theamount is over 5.5 parts by weight, silica suspension and filming on thephotosensitive member tend to occur. If the average particle size isless than 6 nm, silica suspension and filming on the photosensitivemember tend to occur. If the average particle size is more than 200 nm,toner fluidity tends to decrease. In this case, the ignition loss of theinorganic micropowder whose surface has been treated is preferably 1.5to 25 wt %, more preferably 3 to 23 wt %, and further more preferably 5to 20 wt %. If the ignition loss is less than 1.5 wt %, the treatmentagent does not sufficiently exhibit its function, and thus chargeabilityand transfer are difficult to improve. If the ignition loss is more than25 wt %, there is an unprocessed material, and thus developingperformance and chargeability tend to deteriorate.

The average particle size of an inorganic micropowder treated withpolysiloxane and fatty acid or the like is preferably 30 nm to 200 nm,more preferably 40 nm to 140 nm, and further more preferably 40 nm to 90nm. This is because transfer is improved and toner spent on the carriercan be prevented. Furthermore, the inorganic particle preferably is usedin combination with a negatively-chargeable silica micropowder having anaverage particle size of 6 nm to 20 nm. Another preferable constitutionis one in which at least an inorganic micropowder having an averageparticle size of 6 to 20 nm is externally added in an amount of 0.5 to 2parts by weight per 100 parts by weight of toner matrix particles, andan inorganic micropowder that is treated with polysiloxane and a fattyacid or the like and has an average particle size of 30 to 120 nm isexternally added in an amount of 0.5 to 3.5 parts by weight per 100parts by weight of toner matrix particles. The use of a silica whosefunctions have been separated as in this constitution affords a widermargin with respect to handling in development, back-transfer duringtransfer, partial transfer defects, and scattering. This also preventstoner-spent on the carrier. Outside the above ranges, however, thismargin is narrowed, requiring higher precision on the machine side.

Yet another preferable constitution is one in which at least aninorganic micropowder with an average particle size of 6 nm to 20 nm andan ignition loss of 1.5 to 25 wt % is added externally in an amount of0.5 to 2 parts by weight per 100 parts by weight of toner matrixparticles, and an inorganic micropowder that is treated withpolysiloxane and fatty acid or the like and has an average particle sizeof 30 nm to 200 nm and ignition loss of 1.5 to 25 wt % is addedexternally in an mount of 0.5 to 3.5 parts by weight per 100 parts byweight of toner matrix particles. Specifying the ignition loss of thesilica affords a wider margin with respect to back-transfer duringtransfer, partial transfer defects, and scattering. Also, when used incombination with the above-mentioned carrier or wax, this increasestoner-spent resistance, facilitates handling within the developing unit,and increases uniformity in toner density. The occurrence of developingmemory is also suppressed. Outside the above range, however, this marginis narrowed, requiring higher precision on the machine side. Inparticular, the parting action during transfer can be stabilized and thetransfer margin with respect to back-transfer and partial transferdefects can be stabilized.

The transfer margin with respect to back-transfer and partial transferdefects tends to be narrower if the ignition loss is under 1.5 wt % withparticles having an average particle size of 6 to 20 nm. The surfacetreatment tends to be uneven and there tends to be variance in chargingif the ignition loss is over 25 wt %. Preferably, the ignition loss isfrom 1.5 to 20 wt %, and even more preferably from 5 to 19 wt %.

Furthermore, a preferable constitution is one in which apositively-chargeable inorganic micropowder with an average particlesize of 6 nm to 120 nm and an ignition loss of 1.5 to 25 wt % is addedexternally in an amount of 0.5 to 1.5 parts by weight per 100 parts byweight of toner matrix particles. This is because it suppresses excesscharging when the toner is used continuously for an extended period,which further extends the service life of the developer. Another effectis that during transfer it suppresses scattering caused by excesscharging. The effect of adding a positively-chargeable inorganicmicropowder is that the charging stability is improved significantlywhen the toner is used continuously for an extended period by adding thepositively-chargeable inorganic micropowder to the toner. Furthermore,in a tandem electrophotography, it is possible to suppress imagedisruption and transfer defects caused by charge repelling in transfer.If the amount is less than 0.5 parts by weight, the effect is difficultto achieve. If the amount is more than 1.5 parts by weight, fogging indevelopment tends to increase. The ignition loss is preferably 1.5 to 25wt %, and more preferably 5 to 20 wt %.

Preferable examples of positively-chargeable silica include aminosilane,amino-modified silicone oil, silica treated with aminoammonium, titaniumoxide, alumina. In this case, the toner matrix is negatively-chargeable,and in a preferable embodiment, an inorganic micropowder havingchargeability opposite from that of the toner matrix is added.

The average particle size of the inorganic micropowder is obtained byenlarging an electron micrograph, measuring the particle sizes of about100 particles, and calculating the average thereof. Furthermore, thedrying loss of the inorganic powder added as an additive preferably is1.0 wt % or less. If the drying loss is more than 1.0 wt %, imagedeterioration such as fogging tends to be caused in development. Thedegree of hydrophobicity preferably is 70% or more. If the degree ofhydrophobicity is less than 70%, humidity resistance tends to decrease.The drying loss (%) is found as follows. Approximately 1 g of sample isweighed out precisely in a vessel that has been dried, allowed to cool,and precisely weighed. The sample is dried for 2 hours with a hot forcedair drier (105° C.±1° C.), then allowed to cool for 30 minutes in adesiccator, after which it is precisely weighed, and the drying loss iscalculated from the following equation.Drying loss (%)=weight loss on drying (g)/amount of sample (g)×100

The ignition loss is found as follows. Approximately 1 g of sample isplaced and precisely weighed out in a magnetic crucible that has beendried, allowed to cool, and precisely weighed. The sample is ignited for2 hours in an electric furnace set to 500° C., then allowed to cool for1 hour in a desiccator, after which it is precisely weighed, and theignition loss is calculated from the following equation.Ignition loss (%)=weight loss on ignition (g)/amount of sample (g)×100

The moisture adsorption of the treated inorganic micropowder preferablyis no more than 1 wt %, with 0.5 wt % or less being more preferable, 0.1wt % or less even more preferable, and 0.05 wt % or less particularlypreferable. If the amount is more than 1 wt %, there tends to be adecrease in chargeability and filming tends to occur on thephotosensitive member over time. The moisture adsorption apparatus usedto measure the amount of moisture adsorption was a continuousevaporation and adsorption apparatus (Belsorp 18, made by BEL Japan).

The degree of hydrophobicity is measured as follows. 0.2 g of product tobe tested is weighed out precisely in 50 mL of distilled water that hasbeen poured into a 250 mL beaker. Methanol is dripped onto the distalend from a burette immersed in liquid, until the entire amount ofinorganic micropowder is wetted. The system is intermittently and gentlystirred with an electromagnetic stirrer during this time. Thehydrophobicity is calculated with the following equation from the amountof methanol a (ml) needed to completely wet the powder.Hydrophobicity=(a/(50+a))×100 (%)(2) Wax

The wax added to the toner of this embodiment is one with an iodinevalue of 25 or less and a saponification value of 30 to 300. Adding thiswax in an amount of 3 to 20 parts by weight per 100 parts by weight ofbinder resin lessens the repulsion of the toner caused by charge actionduring multilayer toner transfer, and suppresses a decrease in transferefficiency, partial transfer defects during transfer, and back transfer.Also, when this wax is used in combination with the carrier discussedabove, toner-spent occurs less often on the carrier, which extends theservice life of the developer. In addition, handling in the developingunit is facilitated, and there is better uniformity of the image betweenthe leading and trailing sides in development. The wax also reduces theoccurrence of developing memory.

It is preferable for the acid value of the binder resin to be from 1 to40 mgKOH/g. The binder resin preferably is added in an amount of 5 to 20parts by weight per 100 parts by weight of binder resin. Fixability isdifficult to improve if the added amount is below 3 parts by weight, butexceeding 20 parts by weight poses problems with preservation stability.

If the iodine value is greater than 25, there tends to be only minimalreduction in toner repulsion caused by charge action during multilayertoner transfer in primary transfer. Environmental dependence tends to behigh, the chargeability of a material tends to vary greatly duringlong-term continuous use, and the stability of the image tends to beimpaired. Developing memory also is more apt to occur. If thesaponification value is lower than 30, more unsaponified material andhydrocarbons tend to be present, filming tends to occur on thephotosensitive member, and chargeability tends to suffer. Dispersibilityin a charge control agent also tends to be poor, and this can lead tofilming or a decrease in chargeability during continuous use. If thesaponification value is over 300, the dispersibility of the wax in theresin tends to be poor, and there tends to be only minimal reduction intoner repulsion caused by charge action. This also leads to more foggingand toner scattering. If the resin acid value is less than 1 mgKOH/g,there tends to be only minimal reduction in toner repulsion caused bycharge action during multilayer toner transfer. If the resin acid valueis greater than 40 mgKOH/g, environmental resistance tends to suffer,and this leads to more fogging.

The melting point (as found by DSC) preferably is 50 to 120° C. Evenmore preferable is a wax with an iodine value of 15 or less, asaponification value of 50 to 250, and a DSC melting point of 55 to 90°C., and more preferable still is a wax with an iodine value of 5 orless, a saponification value of 70 to 200, and a DSC melting point of 60to 85° C.

It is preferable to use a material that increases in volume by 2 to 30%with a 10° C. change at a temperature over the melting point. The waxexpands rapidly upon changing from a solid to a liquid, so that when itis melted by heat during fixing, the toner particles adhere togethermore tightly, which further improves fixability, parting from the fixingroller is better, and offset resistance is also increased. There tendsto be little effect if the increase in volume is less than 2%, butdispersibility during kneading tends to decrease if the increase is morethan 30%.

The heating loss of the wax at 220° C. preferably is no more than 8 wt%. If the heating loss is greater than 8 wt %, the wax remains in thebinder resin during heating and kneading, greatly reducing the glasstransition point of the binder resin and decreasing the preservationstability of the toner. This has an adverse effect on developingcharacteristics, and produces fogging and photosensitive member filming.The wax with an iodine value of 25 or less and a saponification value of30 to 300 preferably has the following molecular weight characteristicsas determined by gel permeation chromatography (GPC): a number averagemolecular weight of 100 to 5000, a weight average molecular weight of200 to 10,000, a ratio of the weight average molecular weight to thenumber average molecular weight (weight average molecular weight/numberaverage molecular weight) of 1.01 to 8, a ratio of the Z averagemolecular weight to the number average molecular weight (Z averagemolecular weight/number average molecular weight) of 1.02 to 10, and thepresence of at least one molecular weight maximum peak in the molecularweight region from 5×10² to 1×10⁴. Even more preferably, the numberaverage molecular weight is from 500 to 4500, the weight averagemolecular weight is from 600 to 9000, the ratio of the weight averagemolecular weight to the number average molecular weight (weight averagemolecular weight/number average molecular weight) is from 1.01 to 7, andthe ratio of the Z average molecular weight to the number averagemolecular weight (Z average molecular weight/number average molecularweight) is from 1.02 to 9. More preferably still, the number averagemolecular weight is from 700 to 4000, the weight average molecularweight is from 800 to 8000, the ratio of the weight average molecularweight to the number average molecular weight (weight average molecularweight/number average molecular weight) is from 1.01 to 6, and the ratioof the Z average molecular weight to the number average molecular weight(Z average molecular weight/number average molecular weight) is from1.02 to 8. Preservation stability tends to worsen if the number averagemolecular weight is less than 100 or if the weight average molecularweight is more than 200. If the molecular weight maximum peak is locatedbelow 5×10², the dispersibility of the charge control agent with the waxtends to suffer. Also, handling in the developing unit tends to be moredifficult, and toner density cannot be kept as uniform. There tends tobe a decrease in the preservation stability of the toner, an increase inthe toner spent on the carrier, and photosensitive member filming. Ifthe number average molecular weight is greater than 5000, or the weightaverage molecular weight is greater than 10,000, or the ratio of weightaverage molecular weight to number average molecular weight (weightaverage molecular weight/number average molecular weight) is greaterthan 8, or the ratio of Z average molecular weight to number averagemolecular weight (Z average molecular weight/number average molecularweight) is greater than 10, or the molecular weight maximum peak islocated above 1×10⁴, the parting action tends to be weaker and theretends to be a decrease in fixability function, such as fixability andoffset resistance.

The wax preferably is a natural wax such as a meadowfoam oil derivative,carnauba wax, a jojoba oil derivative, Japan wax, beeswax, ozocerite,candelilla wax, montan wax, ceresin wax, and rice wax, a synthetic waxsuch as Fischer-Tropsch wax, or another such material. One type may beused, or a combination of two or more types may be used. It isparticularly preferable to use one or more types of wax selected fromthe group consisting of carnauba wax (DSC melting point of 76 to 90°C.), candelilla wax (66 to 80° C.), hydrogenated jojoba oil (64 to 78°C.), hydrogenated meadowfoam oil (64 to 78° C.), or rice wax (74 to 90°C.).

The saponification value refers to the number of milligrams of potassiumhydroxide (KOH) required to saponify 1 g of sample, and corresponds tothe sum of the acid value and the ester value. To measure thesaponification value, the sample is saponified in an approximately 0.5 Nalcohol solution of potassium hydroxide, after which the excesspotassium hydroxide is titrated with 0.5 N hydrochloric acid.

The iodine value is expressed by the number of grams, per 100 g ofsample, when a halogen is allowed to act on the sample and the amount ofabsorbed halogen is calculated as iodine, and is the number of grams ofiodine absorbed by 100 g of the sample. The greater is this value, thehigher is the degree of fatty acid unsaturation in the sample. Analcohol solution of iodine and mercury chloride (II) or a glacial aceticacid solution of iodine chloride is added to a chloroform or carbontetrachloride solution of the sample, and the iodine that remainsunreacted after the system has been allowed to stand is titrated with asodium thiosulfate standard solution to calculate the amount of absorbediodine.

The heating loss is measured by precisely weighing the sample cell to0.1 mg (W1 mg), putting 10 to 15 mg of sample in this cell, andprecisely weighing to 0.1 mg (W2 mg). The sample cell is placed in adifferential thermal balance, and measurement is commenced with theweighing sensitivity set to 5 mg. Temperature control is performed bythe following program. After measurement, the weight loss is read to 0.1mg (W3 mg) from a chart at the point when the sample temperature reaches220° C. The apparatus used here was a TGD-3000 made by Shinku Riko, thetemperature elevation rate was 10° C./min, the maximum temperature was220° C., the holding time was 1 minute, and the result was calculatedfrom the equation: heating loss (%)=W3/(W3/W2−W1)×100.

The meadowfoam oil derivative preferably is a meadowfoam oil fatty acid,a metal salt of a meadowfoam oil fatty acid, a meadowfoam oil fatty acidester, a hydrogenated meadowfoam oil, a meadowfoam oil amide, ahomomeadowfoam oil amide, a meadowfoam oil triester, a maleic acidderivative of epoxidized meadowfoam oil, an isocyanate polymer of ameadowfoam oil fatty acid polyhydric alcohol ester, or ahalogen-modified meadowfoam oil. These materials are preferred becausethey improve transfer and extend the service life of the developer andoil-less fixing. These can be used singly or in combinations of two ormore types.

Preferable examples of meadowfoam oil fatty acid esters include methyl,ethyl, butyl, glycerol, pentaerythritol, polypropylene glycol,trimethylolpropane esters. A meadowfoam oil fatty acid pentaerythritolmonoester, a meadowfoam oil fatty acid pentaerythritol triester, ameadowfoam oil fatty acid trimethylol propane ester, or the like isparticularly preferable because it affords good cold offset resistanceas well as offset resistance at high temperatures. Also, an isocyanatepolymer of a meadowfoam oil fatty acid polyhydric alcohol esterpreferably is used that is obtained when meadowfoam oil fatty acid andan esterification reaction product with polyhydric alcohol, such asglycerol, pentaerythritol, or trimethylolpropane, are crosslinked byisocyanate such as tolylene diisocyanate (TDI), ordiphenylmethane-4,4′-diisocyanate (MDI). Toner spent on the carrier iscaused less and the two-component developer can have a longer servicelife.

A hydrogenated meadowfoam oil is obtained by hydrogenating meadowfoamoil to convert the unsaturated bonds into saturated bonds. This improvesoffset resistance as well as gloss and optical transmissivity.

A meadowfoam oil amide can be obtained by hydrolyzing meadowfoam oil,and then producing a fatty acid methyl ester by esterification, andfinally reacting this ester with a mixture of concentrated aqueousammonia and ammonium chloride. The melting point of this product can beadjusted by hydrogenation. It is also possible to perform thishydrogenation prior to hydrolysis. A product with a melting point of 75to 120° C. is obtained. A homomeadowfoam oil amide can be obtained byhydrolyzing meadowfoam oil, and then reducing this product to analcohol, and then converting this into a nitrile. This improves offsetresistance as well as gloss and optical transmissivity.

The jojoba oil derivative preferably is a jojoba oil fatty acid, a metalsalt of a jojoba oil fatty acid, a jojoba oil fatty acid ester,hydrogenated jojoba oil, a jojoba oil amide, a homojojoba oil amide, ajojoba oil triester, a maleic acid derivative of epoxidized jojoba oil,an isocyanate polymer of a jojoba oil fatty acid polyhydric alcoholester, or a halogen-modified jojoba oil. These materials are preferredbecause they improve transfer and extend the service life of thedeveloper and oil-less fixing. These can be used singly or incombinations of two or more types.

Preferable examples of jojoba oil fatty acid esters include methyl,ethyl, butyl, glycerol, pentaerythritol, polypropylene glycol,trimethylolpropane esters. A jojoba oil fatty acid pentaerythritolmonoester, a jojoba oil fatty acid pentaerythritol triester, a jojobaoil fatty acid trimethylol propane ester, or the like is particularlypreferable because it affords good cold offset resistance as well asoffset resistance at high temperatures.

Also, an isocyanate polymer of a jojoba oil fatty acid polyhydricalcohol ester preferably is used that is obtained when jojoba oil fattyacid and an esterification reaction product with polyhydric alcohol,such as glycerol, pentaerythritol, or trimethylolpropane, arecrosslinked by isocyanate such as tolylene diisocyanate (TDI), ordiphenylmethane-4,4′-diisocyanate (MDI). Toner spent on the carrier iscaused less and the two-component developer can have a longer servicelife. A hydrogenated jojoba oil is obtained by hydrogenating jojoba oilto convert the unsaturated bonds into saturated bonds. This improvesoffset resistance as well as gloss and optical transmissivity.

A jojoba oil amide can be obtained by hydrolyzing jojoba oil, and thenproducing a fatty acid methyl ester by esterification, and finallyreacting this ester with a mixture of concentrated aqueous ammonia andammonium chloride. The melting point of this product can be adjusted byhydrogenation. It is also possible to perform this hydrogenation priorto hydrolysis. A product with a melting point of 75 to 120° C. isobtained. A jojoba oil amide can be obtained by hydrolyzing jojoba oil,and then reducing this product to an alcohol, and then converting thisinto a nitrile. This improves offset resistance as well as gloss andoptical transmissivity.

A hydroxystearic acid derivative, a glycerol fatty acid ester, a glycolfatty acid ester, a sorbitan fatty acid ester, or another suchpolyhydric alcohol fatty acid ester is the preferred material in thisembodiment, and these can be used singly or in combinations of two ormore types. When used in combination with the above-mentioned carrier,these afford oil-less fixing, extend the service life of the developer,maintain uniformity in the developing unit, and suppress the occurrenceof developing memory.

Preferable examples of derivatives of hydroxystearic acid include methyl12-hydroxystearate, butyl 12-hydroxystearate, propylene glycolmono-12-hydroxystearate, glycerol mono-12-hydroxystearate, and ethyleneglycol mono-12-hydroxystearate. These have the effect of preventingfilming and preventing adhesion to the paper in oil-less fixing.

Preferable examples of glycerol fatty acid esters include glycerolmonostearate, glycerol tristearate, glycerol stearate, glycerolmonopalmitate, and glycerol tripalmitate. These have the effect ofpreventing a decrease in transferability and lessening cold offset atlow temperatures in oil-less fixing.

Preferable examples of glycol fatty acid esters include propylene glycolfatty acid esters such as propylene glycol monopalmitate and propyleneglycol monostearate, and ethylene glycol fatty acid esters such asethylene glycol monostearate and ethylene glycol monopalmitate. Thesehave the effect of affording oil-less fixing, improving lubricity indevelopment, and preventing toner-spent on the carrier.

Preferable examples of sorbitan fatty acid esters include sorbitanmonopalmitate, sorbitan monostearate, sorbitan tripalmitate, andsorbitan tristearate. Other preferable materials include a stearic acidester of pentaerythritol and a mixed ester of adipic acid and stearicacid or oleic acid, and these can be used singly or in combinations oftwo or more types. These have the effect of preventing filming andpreventing adhesion to the paper in oil-less fixing.

Also, an aliphatic amide wax preferably is used in this embodiment. Thisgreatly increases the optical transmissivity in a color image. Inparticular, it promotes smoothness on the surface of a fixed image,allowing a high-quality color image to be obtained. It further preventsthe adhesion of the transfer paper to the fixing roll during fixing,allowing both optical transmissivity and offset resistance to beachieved, and preventing partial transfer defects. When used incombination with the above-mentioned carrier, this affords oil-lessfixing, suppresses the occurrence of toner-spent, extends the servicelife of the developer, maintains uniformity in the developing unit, andsuppresses the occurrence of developing memory.

The aliphatic amide wax preferably is a C₁₆ to C₂₄ saturated ormonounsaturated aliphatic amide such as palmitic acid amide, palmitoleicacid amide, stearic acid amide, oleic acid amide, arachidic acid amide,eicosenoic acid amide, behenic acid amide, erucic acid amide, andlignoceric acid amide, having a melting point of 60 to 120° C., andpreferably 70 to 100° C., and even more preferably 75 to 95° C. Theadded amount preferably is 5 to 20 parts by weight per 100 parts byweight of binder resin. If the melting point is under 60° C., theretends be a decrease in dispersibility in the resin and filming is moreapt to occur on the photosensitive member. If the melting point is over120° C., there tends be a decrease in the smoothness of the fixed imagesurface and optical transmissivity tends to suffer. If the added amountis over 20 parts by weight, preservation stability tends to decrease,but there tends be no effect of the wax if the added amount is less than5 parts by weight.

A wax based on an alkylenebis fatty acid amide of a saturated or a mono-or diunsaturated fatty acid is preferred, examples of which includemethylene-bis-stearic acid amide, ethylene-bis-stearic acid amide,propylene-bis-stearic acid amide, butylene-bis-stearic acid amide,methylene-bis-oleic acid amide, ethylene-bis-oleic acid amide,propylene-bis-oleic acid amide, butylene-bis-oleic acid amide,methylene-bis-lauric acid amide, ethylene-bis-lauric acid amide,propylene-bis-lauric acid amide, butylene-bis-lauric acid amide,methylene-bis-myristic acid amide, ethylene-bis-myristic acid amide,propylene-bis-myristic acid amide, butylene-bis-myristic acid amide,methylene-bis-palmitic acid amide, ethylene-bis-palmitic acid amide,propylene-bis-palmitic acid amide, butylene-bis-palmitic acid amide,methylene-bis-palmitoleic acid amide, ethylene-bis-palmitoleic acidamide, propylene-bis-palmitoleic acid amide, butylene-bis-palmitoleicacid amide, methylene-bis-arachidic acid amide, ethylene-bis-arachidicacid amide, propylene-bis-arachidic acid amide, butylene-bis-arachidicacid amide, methylene-bis-eicosenoic acid amide, ethylene-bis-eicosenoicacid amide, propylene-bis-eicosenoic acid amide, butylene-bis-eicosenoicacid amide, methylene-bis-behenic acid amide, ethylene-bis-behenic acidamide, propylene-bis-behenic acid amide, butylene-bis-behenic acidamide, methylene-bis-erucic acid amide, ethylene-bis-erucic acid amide,propylene-bis-erucic acid amide, and butylene-bis-erucic acid amide.This improves optical transmissivity in a color image and increasesoffset resistance with respect to a fixing roller. This also suppressesthe occurrence of toner-spent on the carrier and extends the servicelife of the developer. The added amount preferably is 3 to 20 parts byweight per 100 parts by weight of binder resin. There tends to be noeffect if the added amount is less than 3 parts by weight, and theretends to be an increase in fogging if the added amount is more than 20parts by weight.

Moreover, the surface smoothness of a fixed image can be improved, andthe optical transmissivity and offset resistance of a color image can bemade even better, by using a wax in which the aliphatic amide and thealkylene bis fatty acid amide are used in a ratio of 3:7 to 7:3. Themelting point here must be higher for the alkylene bis fatty acid amidethan for the aliphatic amide. The melting point of the alkylene bisfatty acid amide being too low not only decreases offset resistance, butthe resin itself is in a state of low softening and is excessivelypulverized during pulverization, so that there tends to be moremicropowder, which leads to a drop in productivity.

In particular, since the aliphatic amide is a material with a lowsoftening point, as compatibility with the resin progresses, the resinitself is plasticized, with the result that offset resistance andpreservation stability decrease, and partial transfer defects occur moreoften during extended use. Accordingly, if an alkylene bis fatty acidamide having a higher melting point is used in combination with analiphatic amide having a lower melting point, there tends to be lessplasticization of the resin itself, partial transfer defects can beprevented during extended use without losing the effect of the aliphaticamide in terms of high optical transmissivity and surface smoothness,and offset resistance and preservation stability can be maintained. Thisalso suppresses the occurrence of toner-spent on the carrier and extendsthe service life of the developer.

Also, a wax obtained by reacting a C₄ to C₃₀ long chain alkyl alcohol,an unsaturated polycarboxylic acid or anhydride thereof, and anunsaturated hydrocarbon wax, or a wax obtained by reacting a long chainalkylamine, an unsaturated polycarboxylic acid or anhydride thereof, andan unsaturated hydrocarbon wax, or a wax obtained by reacting a longchain fluoroalkyl alcohol, an unsaturated polycarboxylic acid oranhydride thereof, and an unsaturated hydrocarbon wax, each of which hasa molecular weight distribution (by GPC) such that the weight averagemolecular weight is from 1000 to 6000, the Z average molecular weight isfrom 1500 to 9000, the ratio of the weight average molecular weight tonumber average molecular weight (weight average molecular weight/numberaverage molecular weight) is from 1.1 to 3.8, the ratio of the Z averagemolecular weight to the number average molecular weight (Z averagemolecular weight/number average molecular weight) is from 1.5 to 6.5,and there is at least one molecular weight maximum peak in the regionfrom 1×10³ to 3×10⁴, and in which the acid value is from 5 to 80mgKOH/g, the melting point is from 60 to 120° C., and the penetration at25° C. is 4 or less, is particularly effective in terms of improvingseparation between the paper and the fixing roller or belt with an imageformed from three layers of color toner on thin paper. Such a wax isalso effective at increasing OHP transmissivity without decreasing hightemperature offset resistance. The addition of this wax also improvesthe fixing characteristics, and particularly high opticaltransmissivity, high gloss, and no offset in oil-less fixing, and doesnot diminish high temperature preservation stability. Also, the offsetof halftone images can be prevented even by using a fluorine- orsilicone-based member for the fixing roller. When used in combinationwith the above-mentioned carrier, this wax affords oil-less fixing,suppresses the occurrence of toner-spent on the carrier, extends theservice life of the developer, maintains uniformity in the developingunit, and suppresses the occurrence of developing memory. Furthermore,charging stability can be obtained over continuous use, allowing bothfixability and charging stability to be achieved at the same time. Also,partability, optical transmissivity, and other aspects of fixability,and charging stability and other aspects of developability can beimproved further by increasing the state of dispersion during theaddition of this wax to the binder resin. The addition of a releaseagent may in some cases lower the dispersibility of other internaladditives, but with the constitution of the additives in thisembodiment, good fixing and development both can be achieved withoutdecreasing the dispersibility.

If the carbon number of the long chain alkyl of the wax is less than 4,the parting action tends to be weak and there tends to be a drop inseparability and high temperature offset resistance. If the carbonnumber of the long chain alkyl is greater than 30, though, there tendsto be a decrease in dispersibility in the binder resin. An acid value ofless than 5 mgKOH/g can lead to a decrease in the amount of charge whenthe toner is used for an extended period, but if the acid value isgreater than 80 mgKOH/g, humidity resistance tends to decrease and theretends to be more fogging under high humidity. The preservation stabilityof the toner tends to decrease if the melting point is below 60° C., butif the melting point is over 120° C., the parting action tends to beweak and the temperature range in which there is no offset tends to benarrower. Toughness tends to decrease and photosensitive member filmingtends to occur over extended use if the penetration at 25° C. is lessthan 4.

If the weight average molecular weight is less than 1000, or the Zaverage molecular weight is less than 1500, or the weight averagemolecular weight/number average molecular weight is less than 1.1, orthe Z average molecular weight/number average molecular weight is lessthan 1.5, or the molecular weight maximum peak is located below 1×10³,there tends to be a decrease in the preservation stability of the tonerand filming tends to occur on the photosensitive member or theintermediate transfer member. Also, handling in the developing unittends to be more difficult, and toner density uniformity tends to drop.Also, developing memory is more likely to occur. If the weight averagemolecular weight is greater than 6000, or the Z average molecular weightis greater than 9000, or the weight average molecular weight/numberaverage molecular weight is greater than 3.8, or the Z average molecularweight/number average molecular weight is greater than 6.5, or themolecular weight maximum peak is located above 3×10⁴, the parting actiontends to be weaker and there tends to be a decrease in fixing offsetresistance. Preferably, the weight average molecular weight is from 1000to 5000, the Z average molecular weight is from 1700 to 8000, the ratioof the weight average molecular weight to number average molecularweight (weight average molecular weight/number average molecular weight)is from 1.1 to 2.8, the ratio of the Z average molecular weight to thenumber average molecular weight (Z average molecular weight/numberaverage molecular weight) is from 1.5 to 4.5, and there is at least onemolecular weight maximum peak between 1×10³ and 1×10⁴, and even morepreferably, the weight average molecular weight is from 1000 to 2500,the Z average molecular weight is from 1900 to 3000, the ratio of theweight average molecular weight to number average molecular weight(weight average molecular weight/number average molecular weight) isfrom 1.2 to 1.8, the ratio of the Z average molecular weight to thenumber average molecular weight (Z average molecular weight/numberaverage molecular weight) is from 1.7 to 2.5, and there is at least onemolecular weight maximum peak between 1×10³ and 3×10³. The alcohol herecan be one having a long chain alkyl, such as octanol, dodecanol,stearyl alcohol, nonacosanol, or pentadecanol. Amines that can be usedpreferably include N-methylhexylamine, nonylamine, stearylamine, andnonadecylamine. Fluoroalkyl alcohols that can be used preferably include1-methoxy-(perfluoro-2-methyl-1-propene), hexafluoroacetone, and3-perfluorooctyl-1,2-epoxypropane. The unsaturated polycarboxylic acidor anhydride thereof can be maleic acid, maleic anhydride, itaconicacid, itaconic anhydride, citraconic acid, citraconic anhydride, or thelike, which can be used singly or in combinations of two or more. Ofthese, maleic acid and maleic anhydride are preferred. Unsaturatedhydrocarbon waxes that can be used preferably include olefins having adouble bond such as ethylene, propylene, or butylenes. The product canbe obtained by polymerizing an unsaturated polycarboxylic acid oranhydride thereof using an alcohol or an amine, and then adding thispolymer to an unsaturated hydrocarbon wax in the presence of dicumylperoxide, tert-butyl peroxyisopropyl monocarbonate, or the like. Theadded amount preferably is 3 to 20 parts by weight per 100 parts byweight of binder resin. The parting effect tends to be minimal if theamount is less than 3 part by weight, but exceeding 20 parts by weightdecreases the fluidity of the toner, and moreover there is no additionaleffect by adding any more.

It is preferable for the dispersed average particle size of the wax inthe binder resin to be from 0.1 to 1.5 μm, for particles smaller than0.1 μm to account for no more than 35% of the dispersed average particlesize distribution, for particles of 0.1 to 2.0 μm to account for atleast 65%, and for particles larger than 2.0 μm to account for no morethan 5%. The particle size and count were found from a cross sectionalmicrograph of the toner taken by TEM. If the dispersed average particlesize is less than 0.1 μm or if particles smaller than 0.1 μm account formore than 35%, there tends to be little effect as a release agent, andgood fixing is difficult to achieve. If the dispersed average particlesize is greater than 1.5 μm and if particles larger than 2.0 μm accountfor more than 5%, the dispersibility of the wax in the resin tends todecrease, and there tends to be only minimal reduction in tonerrepulsion caused by charge action. This also leads to more fogging andtoner scattering. When wax particles in the resin have a elongated oroval structure, it is preferable for the average major axis diameter tobe from 0.5 to 3 μm, for particles smaller than 0.5 μm to account for nomore than 35%, for particles of 0.5 to 3.5 μm to account for at least65%, and for particles larger than 3.5 μm to account for no more than5%. If the average diameter is less than 0.5 μm, and if particlessmaller than 0.5 μm account for more than 35%, there tends to be littleeffect as a release agent, and good fixing is difficult to achieve. Ifthe average diameter is greater than 3 μm, or if particles larger than3.5 μm account for more than 5%, the dispersibility of the wax in theresin tends to decrease, and there tends to be only minimal reduction intoner repulsion caused by charge action. This also leads to more foggingand toner scattering. Also, handling in the developing unit tends to bemore difficult, and developing memory characteristics deteriorate.

(3) Binder Resin

The binder resin in this embodiment preferably contains a polyesterresin in which at least one molecular weight maximum peak is in a regionof 2×10³ to 3×10⁴ in the GPC molecular weight distribution, the contentof components in the high molecular weight region with a molecularweight of at least 3×10⁴ is at least 5% with respect to the entirebinder resin, the weight average molecular weight is from 10,000 to300,000, the Z average molecular weight is from 20,000 to 5,000,000, theratio of the weight average molecular weight to number average molecularweight (weight average molecular weight/number average molecular weight)is from 3 to 100, the ratio of the Z average molecular weight to thenumber average molecular weight (Z average molecular weight/numberaverage molecular weight) is from 10 to 2000, the melting temperature asmeasured by the ½ method with a flow tester that is a constant loadextrusion type of capillary rheometer (this temperature hereinafter isreferred to as the softening point) is from 80 to 150° C., the flowbeginning temperature is from 80 to 120° C., and the glass transitionpoint of the resin is from 45 to 68° C.

Even more preferably, the binder resin contains a polyester resin inwhich the weight average molecular weight is from 10,000 to 200,000, theZ average molecular weight is from 20,000 to 3,000,000, the weightaverage molecular weight/number average molecular weight is from 3 to50, the Z average molecular weight/number average molecular weight isfrom 20 to 1000, the softening point is from 90 to 140° C., the flowbeginning temperature is from 85 to 115° C., and the glass transitionpoint is from 52 to 68° C.

More preferable still is for the binder resin to contain a polyesterresin in which the weight average molecular weight is from 10,000 to150,000, the Z average molecular weight is from 20,000 to 500,000, theweight average molecular weight/number average molecular weight is from3 to 15, the Z average molecular weight/number average molecular weightis from 50 to 1000, the softening point is from 105 to 135° C., the flowbeginning temperature is from 90 to 120° C., and the glass transitionpoint is from 58 to 66° C.

The content of components in the high molecular weight region with amolecular weight of at least 1×10⁵ preferably is at least 3% withrespect to the entire binder resin. Even more preferably, the content ofcomponents in the high molecular weight region with a molecular weightof at least 3×10⁵ preferably is at least 0.5% with respect to the entirebinder resin.

Preferably, the content of components in the high molecular weightregion with a molecular weight of from 8×10⁴ to 1×10⁷ is at least 3%with respect to the entire binder resin, and there is no component witha molecular weight of more than 1×10⁷.

Even more preferably, the content of components in the high molecularweight region with a molecular weight of from 3×10⁵ to 9×10⁶ is at least1% with respect to the entire binder resin, and there is no componentwith a molecular weight of more than 9×10⁶.

Even more preferably, the content of components in the high molecularweight region with a molecular weight of from 7×10⁵ to 6×10⁶ is at least1% with respect to the entire binder resin, and there is no componentwith a molecular weight of more than 6×10⁶.

If the high molecular weight component content is too high, or if themolecules are too large, a high molecular weight component tends toremain behind in kneading and hinder optical transmissivity, and alsotends to lower the efficiency at which the resin itself is manufactured.Also, this component can scratch the developing roller and supply rollerand produce streaks in the image. The dispersibility of the wax alsodecreases.

If the weight average molecular weight of the binder resin is less than10,000, or the Z average molecular weight is less than 20,000, or theweight average molecular weight/number average molecular weight is lessthan 3, or the Z average molecular weight/number average molecularweight is less than 10, or the softening point is lower than 80° C., orthe flow beginning temperature is lower than 80° C., or the glasstransition point is lower than 45° C., there tends to be a decrease indispersibility during kneading, and this leads to more fogging and lowerdurability. Also, the kneading stress is not sufficient during kneading,and thus it tends to be impossible to keep the molecular weight at theproper level. The dispersibility of the wax or charge control agent inthe resin tends to decrease, and there tends to be only minimalreduction in toner repulsion caused by charge action. This also leads tomore fogging and toner scattering. Also, offset resistance and hightemperature preservation stability tend to decrease, the transfer memberis cleaned less properly, and filming tends to occur on thephotosensitive member.

If the weight average molecular weight of the binder resin is greaterthan 300,000, or the Z average molecular weight is greater than5,000,000, or the weight average molecular weight/number averagemolecular weight is greater than 100, or the Z average molecularweight/number average molecular weight is greater than 2000, or thesoftening point is higher than 150° C., or the flow beginningtemperature is higher than 120° C., or the glass transition point ishigher than 68° C., then the load on the machine during treatment may beexcessive, which can lead to a drastic drop in productivity or to adecrease in optical transmissivity in a color image or a decrease infixing strength.

Fixability tends to be further enhanced if the toner that has undergonemelt kneading has a GPC molecular weight distribution in which there isat least one molecular weight maximum peak in the region of 2×10³ to3×10⁴, and there is at least one molecular weight maximum peak orshoulder in the region of 5×10⁴ to 1×10⁶. Preferably, at least onemolecular weight maximum peak is located on the toner low molecularweight side in a range of 3×10³ to 2×10⁴, and even more preferably, in arange of 4×10³ to 2×10⁴.

Preferably, at least one molecular weight maximum peak or shoulder islocated on the toner high molecular weight side in a range of 6×10⁴ to7×10⁵, and even more preferably, in a range of 8×10⁴ to 5×10⁵.

If the molecular weight maximum peak location in the molecular weightdistribution of the toner on the low molecular weight side is less than2×10³, durability tends to decrease, but if this is greater than 3×10⁴,both fixability and optical transmissivity tend to decrease.

If the molecular weight maximum peak or shoulder location in themolecular weight distribution of the toner on the high molecular weightside is less than 5×10⁴, offset resistance tends to decrease, andpreservation stability tends to decrease as well. Developability alsotends to suffer, and there tends to be more fogging. If this is greaterthan 1×10⁶, though, pulverization tends to be difficult, which leads toa drop in productivity.

It is preferable for the content of the component located in the tonerhigh molecular weight range with a high molecular weight of at least5×10⁵ to be no more than 10 wt % with respect to the entire binderresin. If there is a large amount of component located in the highmolecular weight range of at least 5×10⁵, or if the molecules are verylarge, this is a result of the fact that kneading stress is appliedunevenly to the material constituting the toner during kneading,resulting in a poor state of kneading. This impairs the opticaltransmissivity severely. Thus, poor dispersion results in more fogging,decreases transfer efficiency, makes the toner more difficult topulverize, and lowers production efficiency.

More preferably, the content of the high molecular weight component ofat least 5×10⁵ is no more than 5% with respect to the entire binderresin, and even more preferably, the content of the high molecularweight component of at least 1×10⁶ is no more than 1% with respect tothe entire binder resin, or none at all is contained.

Also, in the molecular weight distribution in a toner GPC chromatogram,if we let Ha be the height of the molecular weight distribution of themolecular weight maximum peak located between 2×10³ and 3×10⁴, and Hb bethe height of the molecular weight maximum peak or shoulder locatedbetween 5×10⁴ and 1×10⁶, then Hb/Ha is from 0.15 to 0.9.

If Hb/Ha is less than 0.15, there tends to be a decrease in both offsetresistance and preservation stability, resulting in increased filming ona developing roller and the photosensitive member. If the ratio isgreater than 0.9, pulverization tends to be more difficult, productivitytends to decrease, and cost tends to rise. More preferably, Hb/Ha isfrom 0.15 to 0.7, and even more preferably, Hb/Ha is from 0.2 to 0.6.

In an arrangement in which, in the GPC molecular weight distribution ofthe toner, at least one molecular weight maximum peak is within therange of 2×10³ to 3×10⁴, and at least one molecular weight maximum peakor shoulder is within the range of 5×10⁴ to 1×10⁶, if we focus on themolecular weight curve within a region greater than the molecular weightvalue corresponding to the maximum peak or shoulder of the molecularweight distribution located within the molecular weight range of 5×10⁴to 1×10⁶, and if we assume that the height of the maximum peak orshoulder in this molecular weight distribution is set to a base of 100%,and if we let M90 be the molecular weight corresponding to 90% of theheight of the molecular weight maximum peak or shoulder, and M10 be themolecular weight corresponding to 10% of the height of the molecularweight maximum peak or shoulder, then setting M10/M90 to be from 0.5 to0.8, and further setting (M10−M90)/M90 to be from 0.1 to 7, allowsoptical transmissivity to be ensured, and also allows oil-less fixing inwhich offset is prevented to be achieved without any fixing oil beingrequired. This also suppresses the occurrence of toner-spent on thecarrier and extends the service life of the developer.

Specifying the value M10/M90, and further, the value (M10−M90)/M90 (theslope of the molecular weight distribution curve), makes it possible toquantify the state of molecular cleavage of the ultra-high molecularweight component, and if this value is within the range given above(which suggests that the slope of the molecular weight distributioncurve is steep), cleavage during kneading eliminates ultra-highmolecular weight component that would hamper optical transmissivity, theresult being good optical transmissivity. Moreover, the high molecularweight component that forms the peak or shoulder appearing on the highmolecular weight side contributes to offset resistance, making itpossible to prevent the occurrence of offset in colored toner withoutuse of any oil. This also suppresses the occurrence of toner-spent onthe carrier and extends the service life of the developer.

Furthermore, in the course of the molecular cleavage of the ultra-highmolecular weight component, the wax and charge control agent can bedispersed uniformly in the binder resin, which makes the amount ofcharge more uniform, affords higher resolution, and allows durability tobe maintained even over long-term continuous use. This also improves thecleaning of the transfer member, facilitates handling within thedeveloping unit, and increases uniformity in toner density. Theoccurrence of developing memory also is suppressed. It is also possibleto prevent partial transfer defects and image disruption duringtransfer, and consequently to achieve more efficient transfer.

If the value of M10/M90 is greater than 8, or if (M10−M90)/M90 is lessthan 7, the ultra-high molecular weight component still remains, whichhampers good optical transmissivity. If the value of M10/M90 is smallerthan 0.5, or if (M10−M90)/M90 is less than 0.1, mechanical load duringkneading is too high and productivity tends to fall. This also lowerstoner durability. Preferably, the value of M10/M90 is from 0.5 to 6, and(M10−M90)/M90 is from 0.1 to 4.5. More preferably, the value of M10/M90is from 0.5 to 4.5, and (M10−M90)/M90 is from 0.1 to 3.5.

This affords higher quality digital images and better colorreproduction, prevents toner-spent on the carrier in two-componentdevelopment, and allows both optical transmissivity and offsetresistance to be achieved without the use of an oil for preventingoffset on the fixing roller.

Furthermore, this provides a cleaner process, shortens the transferdistance, prevents partial transfer defects in the transfer step of ahigh-speed tandem transfer process, and results in better transfer.

Characteristics that did not appear in the past can be attained bykneading under a high shearing force in the melt kneading of theabove-mentioned binder resin. This affords both good opticaltransmissivity and offset resistance in a color toner in fixing withoutthe use of an oil. That is, when a binder resin containing a ultra-highmolecular weight component is subjected to high shearing force, thisultra-high molecular weight component is reduced in molecular weight,which results in higher optical transmissivity, and the presence of thisultra-high molecular weight component that has been reduced in molecularweight also provides satisfactory offset resistance. Also, since thereis a ultra-high molecular weight component, high shearing force isproduced during kneading, so that the wax can be dispersed moreuniformly, optical transmissivity is improved, and good transfer can beaccomplished, with no offset and with high image quality and high colorreproduction. This also suppresses the occurrence of toner-spent on thecarrier and extends the service life of the developer.

After the kneading process, the weight average molecular weight of thetoner is to be between 8000 and 180,000, the Z average molecular weightbetween 18,000 and 1,000,000, the ratio of the weight average molecularweight to number average molecular weight (weight average molecularweight/number average molecular weight) between 3 and 80, and the ratioof the Z average molecular weight to the number average molecular weight(Z average molecular weight/number average molecular weight) between 10and 1000. If a toner is kneaded under a high shearing force within thesesuitable ranges, both optical transmissivity and offset resistance canbe achieved in a color toner in fixing without the use of an oil.Preferably, the weight average molecular weight is from 8000 to 100,000,the Z average molecular weight is from 18,000 to 300,000, the weightaverage molecular weight/number average molecular weight is from 3 to60, and the Z average molecular weight/number average molecular weightis from 10 to 500. Even more preferably, the weight average molecularweight is from 10,000 to 40,000, the Z average molecular weight is from20,000 to 80,000, the weight average molecular weight/number averagemolecular weight is from 3 to 30, and the Z average molecularweight/number average molecular weight is from 10 to 50.

If the weight average molecular weight is less than 8000, or if the Zaverage molecular weight is less than 18,000, or if the weight averagemolecular weight/number average molecular weight is less than 3, or ifthe Z average molecular weight/number average molecular weight is lessthan 10, not enough kneading stress tends to be applied, and themolecular weight cannot be maintained at the proper level. Waxdispersibility tends to decrease, as well as offset resistance and hightemperature preservation stability, cleaning of the intermediatetransfer member tends to be poor, and filming tends to occur on thephotosensitive member.

On the other hand, if the weight average molecular weight is greaterthan 180,000, or if the Z average molecular weight is greater than1,000,000, or if the weight average molecular weight/number averagemolecular weight is greater than 80, or if the Z average molecularweight/number average molecular weight is greater than 1000, the chargecontrol agent and other internal additives tend to agglomerate together,leading to a drop in dispersibility, an increase in fogging, a decreasein image density, and poor transfer. This also leads to a decrease infixing strength, optical transmissivity, and gloss.

The binder resin is to contain no more than 5 wt % THF insolubles, andpreferably contains no THF insolubles at all. If the THF insolublecontent is over 5 wt %, the optical transmissivity of a color imagetends to suffer and the image tends to be inferior.

A binder resin that can be used preferably in this embodiment is apolyester resin obtained by polycondensation of an alcohol component anda carboxylic acid component such as a carboxylic acid, carbonate, orcarboxylic anhydride.

Examples of dicarboxylic acids or lower alkyl esters include aliphaticdibasic acids such as malonic acid, succinic acid, glutaric acid, adipicacid, and hexahydrophthalic anhydride, aliphatic unsaturated dibasicacids such as maleic acid, maleic anhydride, fumaric acid, itaconicacid, and citraconic acid, aromatic dibasic acids such as phthalicanhydride, phthalic acid, terephthalic acid, and isophthalic acid, andmethyl esters and ethyl esters of these. Of these, an aromatic dibasicacid such as succinic acid, phthalic acid, terephthalic acid, orisophthalic acid, or a lower alkyl ester of one of these acids, ispreferred. It is preferable to use a combination of succinic acid andterephthalic acid, or of phthalic acid and terephthalic acid.

Examples of trivalent and higher carboxylic acid components include1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid,1,2,4-cyclohexanetricarboxylic acid, 2,5,7-naphtalenetricarboxylic acid,1,2,4-naphtalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid,1,2,5-hexatricarboxylic acid,1,3-dicarboxyl-2-methyl-2-methylenecarboxyprop ane, tetra(methylenecarboxyl)methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid,Enpol trimer acid, and acid anhydrides and alkyl (C₁ to C₁₂) esters ofthese.

Examples of dihydric alcohols include diols such as ethylene glycol,1,2-propylene glycol, 1,3-propylene glycol, 1,3-butylene glycol,1,4-butylene glycol, 1,6-hexanediol, neopentyl glycol, diethyleneglycol, dipropylene glycol, bisphenol A ethylene oxide adduct, andbisphenol A propylene oxide adduct, triols such as glycerol,trimethylolpropane, and trimethylolethane, and mixtures of these. Ofthese, a bisphenol A expressed by Chemical Formula 1, its derivatives,its alkylene oxide adducts, neopentyl glycol, or trimethylolpropane isparticularly preferable.

where R is an ethylene group or propylene group, x and y are each aninteger greater than or equal to 1, and the average value of x+y is from2 to 10.

Examples of trihydric and higher alcohol components include sorbitol,1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol,tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol,2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane,trimethylolpropane, and 1,3,5-trihydroxymethylbenzene.

The polymerization can be performed by a known process, such aspolycondensation or solution polycondensation. This allows a good tonerto be obtained without sacrificing PVC matte resistance or the color ofthe coloring material used in a color toner.

Polycarboxylic acids and polyhydric alcohols usually are used in aproportion such that the ratio of the number of hydroxyl groups to thenumber of carboxyl groups (OH/COOH) is from 0.8 to 1.4.

The molecular weights of the resin, wax, and toner are measured by gelpermeation chromatography (GPC) using a number of kinds of monodispersepolystyrene as the standard sample.

The apparatus used in this measurement is one from the HPLC 8120 series(made by Tosoh), with columns of TSKgel superHM-H H4000/H3000/H2000(diameter: 7.8 mm, 150 mm×3), with an eluant of THF (tetrahydrofuran),at a flow rate of 0.6 mL/min, a sample concentration of 0.1%, and anadded amount of 20 μL, with an RI detector, and at a measurementtemperature of 40° C. As a pretreatment, the sample is dissolved in THFand filtered through a filter of 0.45 μm to remove additives such assilica. The resin component thus obtained is measured. The measurementconditions are such that the molecular weight distribution of the sampleto be measured is included in a range in which a straight line is formedby the count number and the logarithm of the molecular weight in acalibration curve obtained from a plurality of different monodispersepolystyrene standard samples.

The apparatus used to measure the wax obtained by reacting a C₄ to C₃₀long chain alkyl alcohol, an unsaturated polycarboxylic acid oranhydride thereof, and an unsaturated hydrocarbon wax is a GPC-150C madeby Waters, with columns of Shodex HT-806M (8.0 mm I.D.-30 cm×2), with aneluant of o-dichlorobenzene, at a flow rate of 1.0 mL/min, a sampleconcentration of 0.3%, and an added amount of 200 μL, with an RIdetector, and at a measurement temperature of 130° C. As a pretreatment,the sample is dissolved in a solvent and then filtered through asintered metal filter of 0.5 μm. The measurement conditions are suchthat the molecular weight distribution of the sample to be measured isincluded in a range in which a straight line is formed by the countnumber and the logarithm of the molecular weight in a calibration curveobtained from a plurality of different monodisperse polystyrene standardsamples.

The softening point of the binder resin is measured as follows by usinga constant load extrusion type of capillary rheometer made by Shimadzu(CFT500). While heating 1 cm³ of sample at a temperature elevation rateof 6° C./min, a load of approximately 9.8×10⁵ N/m² is applied by aplunger to extrude the sample from a die 1 mm in diameter and 1 mm inlength. Based on the relationship between the piston stroke of theplunger and the temperature elevation characteristics, the temperatureat which the piston stroke starts to rise is termed the flow beginningtemperature (Tfb° C.), and one-half the difference between the lowestvalue on the curve and the flow end point is calculated, and thetemperature at the point where the lowest value in the curve is added tothe one-half value is termed the melting temperature (softening pointTm° C.) by the ½ method.

The glass transition point of the resin is measured by using adifferential scanning calorimeter and following ASTMD3418-82. The glasstransition point refers to the temperature at the point of intersectionbetween an extension of a base line below the glass transition point anda tangent having the maximum slope from the peak rise portion to thepeak top, in the course of measuring hysteresis when the sample isheated to 100° C. and left at that temperature for 3 minutes, afterwhich it is cooled to room temperature at a temperature decrease rate of10° C./min, and then heated at a temperature elevation rate of 10°C./min.

The melting point in an endothermic peak (as determined by DSC) ismeasured with a differential scanning calorimeter DSC-50 made byShimadzu. The sample is heated to 200° C. at a rate of 5° C./min, isheld at that temperature for 5 minutes, and is quenched to 10° C., afterwhich it is allowed to stand for 15 minutes, and then heated at a rateof 5° C./min, and the melting point is found from the endothermic(melting) peak. The amount of the sample put into a cell is 10 mg±2 mg.

Preferable examples of the binder resin used in this embodiment alsoinclude homopolymers or copolymers of various kinds of vinyl monomer.Examples include styrene and derivatives thereof, such as styrene,o-methylstyrene, m-methylstyrene, p-methylstyrene, p-ethylstyrene,2,4-dimethylstyrene, p-n-butylstyrene, p-tert-butylstyrene,p-n-hexylstyrene, p-n-octylstyrene, and p-chlorostyrene, with styrenebeing particularly preferable.

Examples of acrylic monomers include acrylic acid, methacrylic acid,methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate,cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, hexylmethacrylate, 2-ethylhexyl methacrylate, beta-hydroxyethyl acrylate,gamma-hydroxypropyl acrylate, alpha-hydroxybutyl acrylate,beta-hydroxyethyl methacrylate, gamma-aminopropyl acrylate,gamma-N,N-diethylaminopropyl acrylate, ethylene glycol dimethacrylate,and tetraethylene glycol dimethacrylate. A copolymer of styrene andbutyl acrylate is preferable as the styrene-acrylic copolymer for thepurposes of the present invention, and particularly one that contains 75to 85 wt % styrene and 15 to 25 wt % butyl acrylate.

(4) Charge Control Agent

A charge control agent is added in this embodiment for the purpose ofcontrolling the toner charge and for ensuring stronger oil-less fixing.An acrylsulfonic acid-based polymer is a preferable material, and avinyl copolymer of a styrene-based monomer and an acrylic acid-basedmonomer having sulfonic acid groups as polar groups is preferred. Thecharacteristics are particularly preferable with a copolymer ofacrylamide-2-methylpropanesulfonic acid. When used in combination withthe above-mentioned carrier, this facilitates handling within thedeveloping unit, and increases uniformity in toner density. Theoccurrence of developing memory also is suppressed.

The metal salt of a salicylic acid derivative shown in Chemical Formula2 can be used as a preferable material.

where R¹, R², and R³ are each independently a hydrogen atom or a linearor branched C₁ to C₁₀ alkyl group or allyl group, and Y is at least oneelement selected from zinc, nickel, cobalt, copper, and chromium.

The metal salt of a benzylic acid derivative shown in Chemical Formula 3can be used as a preferable material.

where R¹ and R⁴ are each independently a hydrogen atom, a linear orbranched C₁ to C₁₀ alkyl group, or an aromatic ring that may have asubstituent, R² and R³ are aromatic rings that may be substituted, and Xis an alkali metal.

In the metal salt of a salicylic acid derivative, examples of C₁ to C₁₀alkyl groups include a methyl group, ethyl group, n-propyl group,isopropyl group, n-butyl group, isobutyl group, sec-butyl group, andtert-butyl group. Examples of the metal Y include zinc, nickel, cobalt,copper, and chromium, with zinc and chromium being preferred. In themetal salt of a benzylic acid derivative, R¹ to R⁴ can be a benzenering, and examples of the alkali metal X include lithium, sodium, andpotassium, with potassium being preferred. This constitution ensures awide range of non-offset temperature in oil-less fixing, and alsoprevents image disruption caused by a charge action during fixing. Thisis believed to be the effect of the charge polarity of the metal saltand functional group having an acid value possessed by the wax. Thisalso reduces the amount of charge in continuous use. The added amount ofthis agent is preferable from 0.5 to 5 parts by weight per 100 parts byweight of binder resin. 1 to 4 parts by weight is even more preferable,and 3 to 4 parts by weight is better yet. There tends to be no chargeaction effect if the amount is less than 0.5 parts by weight, but colorimpurity tends to be pronounced in a color image if the amount isgreater than 5 parts by weight.

(5) Pigment

Examples of the pigment used in this embodiment include carbon black,iron black, graphite, nigrosine, a metal complex of an azo dye,arylamide acetoacetate monoazo yellow pigments such as C.I. pigmentyellow 1, 3, 74, 97, and 98, arylamide acetoacetate diazo yellowpigments such as C.I. pigment yellow 12, 13, 14, and 17, C.I. solventyellow 19, 77, and 79, and C.I. disperse yellow 164.Abenzimidazolone-based pigment such as C.I. pigment yellow 93, 180, or185 is particularly preferable because it is effective with respect tofilming on the photosensitive member.

One or more types of red pigment such as C.I. pigment red 48, 49:1,53:1, 57, 57:1, 81, 122, and 5, red dyes such as C.I. solvent red 49,52, 58, and 8, and blue dyes or pigments such as phthalocyanine or aderivative thereof, such as C.I. pigment blue 15:3 are added. The addedamount preferably is from 3 to 8 parts by weight per 100 parts by weightof binder resin.

(6) Powder Properties of Toner

The constitution in this embodiment is such that the volume averageparticle size of a toner containing at least a binder resin, a colorant,and a wax is from 3.5 to 6.5 μm, the toner contains from 30 to 80%particles (in the number distribution) of 5.04 μm or smaller, containsfrom 5 to 35% particles (in the number distribution) of 3.17 μm orsmaller, and contains no more than 35 vol % particles whose size isbetween 6.35 and 10.1 μm. The constitution in a more preferable exampleis such that a toner particle contains no more than 30 vol % particleswhose size is between 6.35 and 10.1 μm, and contains no more than 5 vol% particles of 8 μm or larger in the number distribution. This affordsan image of high resolution, prevents back-transfer in tandem transfer,prevents partial transfer defects, and allows oil-less fixing. Attainingboth good image quality and good transfer becomes difficult if thevolume average particle size is greater than 6.5 μm, but the tonerparticles tend to be difficult to handle in development if the volumeaverage particle size is less than 3.5 μm. Attaining both good imagequality and good transfer becomes difficult if the content of particlesof 5.04 μm or smaller in the number distribution is less than 30%, butthe toner particles tend to be difficult to handle in development if thecontent is over 80%. Carrier fouling also tends to occur. Attaining bothgood image quality and good transfer becomes difficult if the content ofparticles of 3.17 μm or smaller in the number distribution is more than5%, but the toner particles tend to be difficult to handle indevelopment if the content is over 35%. Attaining both good imagequality and good transfer becomes difficult if toner particles having asize of 6.35 to 10.1 μm account for more than 35 vol %. Furthermore,attaining both good image quality and good transfer becomes difficult iftoner particles having a size of 6.35 to 10.1 μm account for more 30 vol% and the content of particles of 8 μm or larger in the numberdistribution is greater than 5 vol %.

This constitution is preferably such that the ratio SSt of the specificsurface area St corresponding to a true sphere calculated from thevolume average particle size (St=6/(true specific gravity×volume averageparticle size)) to the measured specific surface area of the producedtoner matrix (SSt=St/(specific surface area of pulverized toner)) isfrom 0.4 to 0.95. This ratio more preferably is from 0.5 to 0.85, andeven more preferably from 0.55 to 0.8. The particles tend to be close tospherical if the ratio is over 0.95, which leads to a decrease inchargeability during continuous use, and to problems such as scatteringduring transfer. If the ratio is smaller than 0.4, the particles tend tobe too amorphous in shape, or there tends to be too much excessivelypulverized micropowder.

The coefficient of variation of the volume particle size distribution ofthe toner preferably is from 16 to 32%, and the coefficient of variationof the number particle size distribution preferably is from 18 to 35%.More preferably, the coefficient of variation of the volume particlesize distribution is from 18 to 24%, and the coefficient of variation ofthe number particle size distribution is from 20 to 26%. Mostpreferably, the coefficient of variation of the volume particle sizedistribution is from 18 to 22%, and the coefficient of variation of thenumber particle size distribution is from 20 to 24%.

The coefficient of variation is a value obtained by dividing thestandard deviation of the toner particle size by the average particlesize. This value is found on the basis of particle sizes measured with aCoulter Counter (made by Coulter). The standard deviation is expressedas the square root of the value obtained by measuring n-number ofparticle systems and dividing the sum of the squares of the differenceof the various measured values from the average value by (n−1). That is,the coefficient of variation expresses how wide the particle sizedistribution is, and when the coefficient of variation of the volumeparticle size distribution is less than 16%, or when the coefficient ofvariation of the number particle size distribution is less than 18%,manufacture becomes difficult and costs rise. When the coefficient ofvariation of the volume particle size distribution is greater than 32%,or when the coefficient of variation of the number particle sizedistribution is greater than 35%, the particle size distribution becomesbroader, causing strong toner agglomeration, filming on thephotosensitive member, and transfer defects, and making it difficult torecover residual toner in a cleaner-less process.

The micropowder in a toner affects the fluidity of the toner, imagequality, storage stability, filming of the photosensitive member, thedeveloping roller, and the transfer member, characteristics over time,transferability, and especially multilayer transferability in tandemtransfer. It also affects optical transmissivity, gloss, and offsetresistance in oil-less fixing. With a toner containing a wax or otherrelease agent for the sake of oil-less fixing, the amount of micropowderaffects tandem transferability. If the amount of micropowder is toolarge, much wax that cannot be dispersed tends to be exposed on thetoner surface, resulting in filming on the photosensitive member andtransfer member. Furthermore, since a micropowder readily adheres to ahot roller, it tends to cause offset. Also, in tandem transfer, toneragglomeration tends to be strong, and this tends to result in transferdefects in the second color during multilayer transfer. If the amount ofmicropowder is too small, though, this can lead to a decrease in imagequality.

The particle size distribution is measured with a Coulter Counter modelTA-II (made by Coulter), and is measured by connecting to a computer andan interface (made by Nikkaki) that outputs the number distribution andvolume distribution. About 2 mg of toner sample is added to about 50 mLof electrolyte to which a surfactant (sodium laurylsulfate) has beenadded in a concentration of 1 wt %, and the electrolyte in which thesample has been suspended is subjected to a dispersal treatment forabout 3 minutes with an ultrasonic disperser. An aperture of 70 μm wasused with the Coulter Counter model TA-II. With an aperture of 70 μm,the particle size distribution measurement range is from 1.26 to 50.8μm, but the region below 2.0 μm is impractical because external noiseand so forth result in low measurement precision and reproducibility.Thus, the measurement range was set at 2.0 to 50.8 μm.

Compression, which is calculated from static bulk density and dynamicbulk density, is an index of toner fluidity. The fluidity of a toner isaffected by the particle size distribution of the toner, the tonerparticle shape, additives, and the type and amount of wax. Compressionis low and toner fluidity is high when the particle size distribution ofthe toner is narrow and there is little micropowder, or when there arefew bumps on the surface of the toner and the particle shape is close tospherical, or when a large quantity of additives are added, or when theparticle size of the additives is small. Compression preferably is from5 to 40%, and even more preferably 10 to 30%. This allows both oil-lessfixing and tandem multilayer transfer to be achieved. If the compressionis less than 5%, fixability tends to decrease, and opticaltransmissivity tends to be particularly poor. There also tends to bemore toner scattering from the developing roller. If the compression isgreater than 40%, though, transferability tends to decrease, and partialtransfer defects and the like tend to occur in tandem transfer.

(7) Carrier

A carrier having a carrier core and a resin coating layer composed of afluorine-modified silicone resin containing an aminosilane couplingagent can be used preferably as the resin coated carrier in thisembodiment. Examples of the carrier core include an iron powder-basedcarrier core, a ferrite-based carrier core, a magnetite-based carriercore, and a resin dispersed type of carrier core comprising a magneticmaterial dispersed in a resin. Examples of the ferrite-based carriercore here generally are expressed by the following formula.(MO)_(x)(Fe₂O₃)_(y)

-   -   where M is at least one element selected from Cu, Zn, Fe, Mg,        Mn, Ca, Li, Ti, Ni, Sn, Sr, Al, Ba, Co, Mo, and the like. X and        Y indicate the mole-based weight ratio and satisfy the condition        X+Y=100.

At least one oxide of M (selected from Cu, Zn, Fe, Mg, Mn, Ca, Li, Ti,Ni, Sn, Sr, Al, Ba, Co, Mo, and the like) is mixed with the main rawmaterial Fe₂O₃, and this mixture is used as the raw material for theferrite-based carrier core. An example of a method for manufacturing aferrite-based carrier core is first to blend suitable amounts of the rawmaterial such as the above-mentioned oxides, pulverize and mix thesecomponents for 10 hours in a wet ball mill, dry the mixture, and thenkeep this product at 950° C. for 4 hours. This product is pulverized for24 hours in a wet ball mill, and polyvinyl alcohol (as a binder), anantifoaming agent, a dispersant, or the like is added to create a slurrywith a raw material particle size of 5 μm or less. This slurry isgranulated and dried, and these granules are kept at 1300° C. for 6hours under a controlled oxygen concentration, and then pulverized andgraded to the desired particle size distribution.

It is essential that the resin used for the resin coating layer of thepresent invention be a fluorine-modified silicone resin. Thisfluorine-modified silicone resin preferably is a crosslinkablefluorine-modified silicone resin obtained by reacting apolyorganosiloxane with an organosilicon compound containingperfluoroalkyl groups. The ratio in which the polyorganosiloxane and theorganosilicon compound containing perfluoroalkyl groups are combinedpreferably is at least 3 parts by weight and no more than 20 parts byweight of the organosilicon compound containing perfluoroalkyl groupsper 100 parts by weight of polyorganosiloxane.

The polyorganosiloxane preferably is at least one repetition unitselected from Chemical Formulas 4 and 5 below.

-   -   where R¹ and R² are each a hydrogen atom, halogen atom, hydroxy        group, methoxy group, or C₁ to C₄ alkyl group or phenyl group,        R³ and R⁴ are each a C₁ to C₄ alkyl group or phenyl group, and m        is a positive integer (preferably in the range from 2 to 500,        more preferably in the range from 5 to 200) indicating the        average degree of polymerization.

where R¹ and R² are each a hydrogen atom, halogen atom, hydroxy group,methoxy group, or C₁ to C₄ alkyl group or phenyl group, R³, R⁴, R⁵, andR⁶ are each a C₁ to C₄ alkyl group or phenyl group, and n is a positiveinteger (preferably in the range from 2 to 500, more preferably in therange from 5 to 200) indicating the average degree of polymerization.

Examples of the perfluoroalkyl group-containing organosilicon compoundinclude CF₃CH₂CH₂Si(OCH₃)₃, C₄F₉CH₂CH₂Si(CH₃)(OCH₃)₂,C₈F₁₇CH₂CH₂Si(OCH₃)₃, C₈F₁₇CH₂CH₂Si(OC₂H₅)₃, and(CH₃)₂CF(CF₂)₈CH₂CH₂Si(OCH₃)₃, but one that has a trifluoropropyl groupis particularly preferable.

In this embodiment, an aminosilane coupling agent is contained in theresin coating layer. This aminosilane coupling agent may be a knownagent such as γ-(2-aminoethyl)aminopropyltrimethoxysilane,γ-(2-aminoethyl)aminopropylmethyldimethoxysilane, andoctadecylmethyl[3-(trimethoxysilyl)propyl] ammonium chloride (from thetop, SH6020, SZ6023, and AY43-021, all made by Dow Corning ToraySilicone), and KBM602, KBM603, KBE903, and KBM573 (made by Shin-EtsuSilicone). A primary amine is particularly preferable. The polarity isweak with secondary or tertiary amines substituted with a methyl group,ethyl group, phenyl group, or the like, so that these have little effecton the charge rise characteristics with the toner. Also, when the aminogroup portion is an aminomethyl group, aminoethyl group, or aminophenylgroup, then the silane coupling agent has a primary amine at its veryend, but the amino groups in the straight-chain organic groups extendingfrom the silane do not contribute to the charge rise characteristicswith the toner, but conversely are affected by moisture under highhumidity, so that although the carrier initially may have been capableof imparting a charge with the toner due to the amino group at the end,this charge imparting capability decreases after repeated printings, sothat the carrier ends up having short service life.

The use of an aminosilane coupling agent such as this andfluorine-modified silicone resin in combination ensures a sharp chargequantity distribution with respect to the toner, while allowing negativechargeability to be imparted, results in a fast charge rise insupplementally added toner, and reduces the amount of toner consumption.Furthermore, the aminosilane coupling agent has an effect similar tothat of a crosslinking agent, and therefore increases the degree ofcrosslinking of the fluorine modified silicone resin layer serving as abase resin, further increases the coating resin hardness, reduces wear,separation, and so forth that result from extended use, improvesresistance to toner-spent, suppress a decrease in chargeability,stabilizes charging, and increases durability. Furthermore, if this isused in combination with a toner to which a certain amount or more ofspecific additive has been added, handling in the developing unit isfacilitated, there is better uniformity in density between the leadingand trailing sides in developing an image. Also, there is a reduction inwhat is known as developing memory, in which a history remains after asolid image is acquired. If this is used in combination with a toner towhich a certain amount or more of low-melting point wax has been addedfor oil-less fixing, it is possible to prevent toner-spent on thecarrier and improve the service life. The aminosilane coupling agent isused in a proportion of 5 to 40 wt %, and preferably 10 to 30 wt %, withrespect to the resin. The aminosilane coupling agent tends to have noeffect if this proportion is less than 5 wt %, but if 40 wt % isexceeded, the crosslinking of the resin coating layer tends to be toohigh, making it more likely that charge-up occurs, and causing imagedefects such as an insufficient development.

The resin coating layer also can contain conductive microparticles inorder to stabilize charging and to prevent charge-up. Examples of suchconductive microparticles include carbon blacks such as oil furnacecarbon and acetylene black, semiconductive oxides such as titanium oxideand zinc oxide, and materials in which the surface of a powder such astitanium oxide, zinc oxide, barium sulfate, aluminum borate, orpotassium titanate is coated with tin oxide, carbon black, or a metal.The specific resistance of these particles preferably is 10¹⁰ Ω·cm orless. When conductive microparticles are used, they are preferablycontained in an amount of 1 to 15 wt %. If a certain amount ofconductive microparticles are contained in the resin coating layer, theytend to increase the hardness of the resin coating layer by a fillereffect, but if the amount is over 15 wt %, they tend conversely tohinder the formation of the resin coating layer and cause a decrease inadhesiveness or hardness. Furthermore, if the conductive microparticlesare contained in too large an amount in a full-color developer, theytend to cause toner color stains in the toner that is transferred andfixed to the paper surface.

The use in combination with a toner to which the inorganic micropowderdiscussed above has been added lowers toner-spent on the carrier causedby the low-melting point component more, and ensures a longer servicelife. During mixing and stirring, there is an effect of improving thecharge rise characteristics and dot reproducibility, and reducingfogging.

The average particle size of the carrier used in the present inventionpreferably is 20 to 70 μm. If the average particle size of the carrieris less than 20 μm, the ratio of microparticles in the carrier particledistribution tends to be high and the amount of magnetization percarrier particle tends to be small, so that the carrier is more prone tobeing developed on the photosensitive member. If the average particlesize of the carrier is more than 70 μm, however, the specific surfacearea of the carrier particles tends to be small and their toner holdingpower tends to be weak, resulting in toner scattering. Also, in fullcolor development including a large amount of solid image, the solidimage is reproduced in a particularly poor manner, which is notpreferable.

There are no particular restrictions on how the coating layer is formedon the carrier core, and any known coating method may be employed.Examples include wet coating methods such as an immersion method inwhich a powder (the carrier core) is immersed in a solution for forminga coating layer, a spray method in which a solution for forming acoating layer is sprayed onto the surface of the carrier core, afluidized bed method in which a solution for forming a coating layer issprayed while the carrier core is fluidized with air, and a kneadercoater method in which the carrier core and a solution for forming acoating layer are mixed in a kneader coater and the solvent is thenremoved; and a dry coating method in which a powdered resin and thecarrier core are mixed at a high speed and the frictional heat thusgenerated is utilized to fuse a coating of the powdered resin to thesurface of the carrier core. Although any of these methods can beapplied, it is particularly preferable to use a wet coating method forcoating with a fluorine-modified silicone resin containing anaminosilane coupling agent as in the present invention.

There are no particular restrictions on the solvent used in the coatingliquid for forming a coating layer, as long as it is one that willdissolve the coating resin, and the solvent may be selected as dictatedby the coating resin being used. Examples of the solvent typicallyinclude aromatic hydrocarbons such as toluene and xylene, ketones suchas acetone and methyl ethyl ketone, and ethers such as tetrahydrofuranand dioxane.

The amount of resin coating in the present invention is from 0.1 to 5.0wt % with respect to the carrier core. If the amount of resin coating isless than 0.5 wt %, a uniform coating cannot be formed on the carriersurface, and the influence of the characteristics of the carrier coretends to be so strong that the effect of the fluorine-modified siliconeresin and the aminosilane coupling agent of the present invention cannotbe fully realized. If the amount is more than 5.0 wt %, the coatinglayer tends to be too thick, granulation tends to occur among thecarrier particles, and there tends to be a tendency for uniform carrierparticles not to be obtained.

After coating the surface of the carrier core with the fluorine-modifiedsilicone resin containing an aminosilane coupling agent in this manner,it is preferable to perform a baking treatment. There are no particularrestrictions on the means for performing this baking treatment, and itmay involve either external or internal heating. For example, the bakingmay be performed by using an electric furnace with a fixed or afluidized bed, a rotary kiln electric furnace, or a burner furnace, ormicrowaves may be used. As to the temperature in the baking treatment,however, in order for the effect of the fluorosilicone (improving thetoner-spent resistance of the resin coating layer) to be exhibitedefficiently, the treatment preferably is conducted at a high temperatureof from 200 to 350° C., and more preferably from 220 to 280° C. Atreatment duration of 0.5 to 2.5 hours is suitable. The hardness of thecoating resin itself tends to decrease if the treatment temperature istoo low, but charging tends to decrease if the treatment temperature istoo high.

(8) Kneading Method

Kneading under a high shearing force allows the added wax to be morefinely dispersed. Thorough dispersion can be accomplished by optimallysetting the kneading conditions, including the roll temperature,temperature gradient, rotational speed, and load current, and thesoftening point and glass transition point of the binder resin. “Highshearing force” refers to a kneading force that acts on a binder resinor other toner material when rolls that are spaced at a narrow gap arerotated at a high speed, and refers to the force produced when thematerial is squeezed through the narrow gap, and to the shearing forceimparted by rotating rolls having a rotational speed differential. Akneading force is produced that was unattainable with a conventionalbiaxial extruder. This makes it possible to produce high and lowmolecular weight components for the binder resin.

More specifically, there are two opposing rolls that are rotating indifferent directions and are capable of heating or cooling. Atemperature differential is provided between the temperature of one roll(RL1) and the other roll (RL2). The roll (RL1) and the roll (RL2) arerotated at different peripheral speeds so that kneading is performedbetween the two rolls. Furthermore, the roll (RL1) has a temperaturedifferential between its front and rear portions.

The speed ratio of the two rolls is from 1.1 times to 2.5 times so thatan appropriate shearing force is generated during kneading, the binderresin undergoes molecular cleavage, there is an increase in thedispersibility of the colorant and other internal additives, anddevelopment and fixing are improved. This constitution is such that theroll on which the heated and melted toner adheres has a higher rotationratio. If the ratio is less than 1.1, the proper shearing force tendsnot to be produced, dispersibility tends not to be increased, andoptical transmissivity tends to suffer. Conversely, if the ratio is over2.5 times, there tends to be a sharp reduction in productivity,dispersibility tends not to increase, and development tends to suffer.

If the kneading here is performed such that the ratio of load currentvalues applied to the two rolls is between 1.25 and 10, the appropriateshearing force tends to be applied and the dispersibility of theinternal additives tends to be improved. If the ratio is below thisrange, there tends to be no increase in dispersibility and opticaltransmissivity tends to suffer. Productivity also tends to decrease.Conversely, if the ratio is over this range, the rollers tend to besubjected to excessive load, and too much ultra-high molecular weightcomponent tends to be further lowered in molecular weight, with theresult being a decrease in offset resistance, so that offset tends tooccur.

FIG. 3 is a simplified oblique view of a toner melt-kneading process,FIG. 4 is a plan view seen from the above, FIG. 5 is a side view seenfrom the left side, and FIG. 6 is a cross-sectional view in a windingstate. 601 is a metering supply unit for toner raw material, 602 is aroll (RL1), 603 is a roll (RL2), and 604 is a molten toner film adheringaround the roll (RL1). The roll 602 rotates clockwise in FIG. 3, whilethe roll 603 rotates counterclockwise.

In FIG. 4, 602-1 is the front half of the roll (RL1) (the upstream partin the direction of raw material conveyance), 602-2 is the rear half ofthe roll (RL1) (the downstream part in the direction of raw materialconveyance), 603-1 is the front half of the roll (RL2) (the upstreampart in the direction of raw material conveyance), 603-2 is the rearhalf of the roll (RL2) (the downstream part in the direction of rawmaterial conveyance), 605 is an inlet for a heating medium for heatingthe front half 602-1 of the roll (RL1), 606 is an outlet for the heatingmedium that has heated the front half 602-1 of the roll (RL1), 607 is aninlet for a medium for heating or cooling the rear half 602-2 of theroll (RL1), 608 is an outlet for the medium that has heated or cooledthe rear half 602-2 of the roll (RL1), 618 is an inlet for a heatingmedium for heating the front half 603-1 of the roll (RL2), 619 is anoutlet for the heating medium that has heated the front half 603-1 ofthe roll (RL2), 609 is an inlet for a medium for heating or cooling therear half 603-2 of the roll (RL2), and 610 is an outlet for the mediumthat has heated or cooled the rear half 603-2 of the roll (RL2).

In FIG. 5, 611 is a spiral groove formed on the roll surface, the depthof which is about 2 to 10 mm. The spiral groove 611 is preferable forsmoothly conveying the material from the right end of a materialcharging section to the left end of a discharge section during thekneading of the toner. 603-1 applies enough heat for the raw material toadhere efficiently around the roll.

The raw material discharged from the metering supply unit 601 fallsthrough an opening 614 into the vicinity of the end on the roll (RL1)602-1 side while going through a raw material supply feeder 613, asshown by arrow 615. 616 represents the length of the opening of thesupplying feeder. This length preferably is equal to from one-half tofour times the roll radius. If the length is too short, there tends tobe a rapid increase in the amount of material that drops down from thegap between the two rollers before it has been melted. If the length istoo great, the material tends to separate in the midst of being conveyedby the raw material feeder, so that uniform dispersion tends not to beobtained.

In FIG. 6, the dropping position is set to a point within a range of 20to 80 degrees from the point at which the two rolls of the roll (RL1)602 are closest to each other, as indicated by the arrow. If the angleis less than 20 degrees, there tends to be a rapid increase in theamount of the material dropping through the gap between the two rolls.If the angle is greater than 80 degrees, however, there tends to be morebillowing of toner powder while it is being dropped, and this powdertends to foul the surrounding area. A cover 617 is provided so as tocover an area wider than the length of the opening portion 616. Thecover is not depicted in FIG. 5.

The toner raw material from the metering supply unit 601 falls throughthe opening 614 while going through the raw material supply feeder 613.The toner raw material that has fallen is charged in the vicinity of theend on the roll (RL1) 602-1 side. The resin is melted by the heat of602-1 and the compressive shearing force of the roll (RL2) 603-1, andadheres around the front half 602-1 of the roll (RL1). A toner pool 612is formed between the rolls. This state spreads to the end of the rearhalf 602-2 of the roll (RL1), and the toner separates in a solid piecefrom the rear half 602-2 of the roll (RL2) that has been heated orcooled at a temperature lower than that of the front half 602-1 of theroll (RL1). During this process, the roll 603-2 is cooled to roomtemperature or lower. The clearance between the roll (RL1) 602 and theroll (RL2) 603 is from 0.1 to 0.9 mm. In this example, the raw materialcharge was 10 kg/h, the diameter of the rolls RL1 and RL2 was 140 mm,and the length was 800 mm.

(9) Pulverization

The two-component developer pertaining to this embodiment preventstoner-spent on the carrier and allows oil-less fixing even when tonerwith a small particle size is used.

The following is an example of how this pulverization is accomplished.To achieve a small particle size and a sharp particle size distribution,the toner composition is melt and kneaded, after which it is pulverizedto the required particle size distribution with a pulverizer equippedwith a cylindrical rotor that has a bumpy surface and rotates at a highspeed, a cylindrical stator that has a bumpy surface and shares itscentral axis with the rotor and is disposed on the outside of the rotorwith a gap of 0.5 to 40 mm therebetween, a supply inlet through whichthe toner to be pulverized flows, and a discharge outlet for dischargingthe pulverized toner. The constitution here is such that some means isprovided for lessening the agglomeration of the toner to be pulverizedbefore this toner flows through the supply inlet, and the toner flowsthrough the supply inlet and is pulverized to the required particle sizedistribution.

The purpose of the means for lessening the agglomeration of the toner tobe pulverized is to allow the charge to be removed from the powder withan evaporative medium such as water vapor, ethanol, iso-propyl alcohol,n-butyl alcohol, sec-butyl alcohol, or iso-butyl alcohol, before thetoner to be pulverized flows through the supply inlet. The toner to bepulverized is allowed to flow through the supply inlet after being madeto adhere or mixed by being sprayed in the form of a mist. Also, in amethod in which the toner to be pulverized is subjected to a vibrationmeans before flowing through the supply inlet, in which case examples ofthe vibration means include ultrasonic vibration and mechanicalvibration. A vibration apparatus is provided to the piping before thetoner to be pulverized passes through the pipe and flows through thesupply inlet of the pulverizing section, and the toner to be pulverizedis dispersed while flowing through the supply inlet. Another method isto supply and mix an inorganic micropowder into the toner to bepulverized before the toner flows through the supply inlet, and thenallow the toner to flow through the supply inlet and be pulverized. Oneof the materials discussed above is suitable as this inorganicmicropowder. In the pulverization of the toner, the constitution is suchthat an inorganic micropowder is supplied to and mixed with the toner tobe pulverized before the toner flows through the supply inlet, and thenthe toner is allowed to flow through the supply inlet and is pulverizedto the required particle size distribution. As a result, the toner to bepulverized is in a uniformly dispersed state when it enters thepulverizing section having the rotor, and the toner is uniformlypulverized by the eddy produced by the rotor. This makes possiblepulverization to a small particle size, and pulverization in a state inwhich the raw powder has been sharply cut.

The inorganic micropowder that is supplied and mixed in here preferablyis a silica or titanium oxide micropowder that has an average particlesize of 8 to 40 μm and an ignition loss of 0.5 to 25 wt %. The use asilica or titanium oxide micropowder that has been surface treated withone or more of a fatty acid ester, fatty acid amide, and fatty acidmetal salt is preferred. A silica or titanium oxide micropowder that hasbeen surface treated with a silicone oil is an even more preferablematerial for the inorganic micropowder. Also, an inorganic micropowderhaving the opposite charge polarity from that of the toner matrixparticles is an effective way to lessen the charge of the toner to bepulverized. Constant-amount cut out tends to be unstable if the averageparticle size is less than 8 nm, but pulverization uniformity tends tobe poor if the average particle size is greater than 40 nm. Themicropowder tends to scatter if the ignition loss is less than 0.5 wt %,but micropowder agglomeration tends to be severe and the toner to bepulverized is not supplied uniformly if the ignition loss is greaterthan 25 wt %.

This inorganic micropowder adheres to the toner surface in a state ofelectrostatic adhesion, without being affixed to the toner matrix. Theinorganic micropowder preferably is supplied in an amount of about 0.1to 5 wt % of the supply amount of the toner to be pulverized.

The gap between the convex part of the rotor and the convex part of thestator is 0.5 to 40 mm, and preferably 0.5 to 10 mm, and even morepreferably 0.5 to 6 mm. This improves pulverization efficiency and makesthe particles more spherical. There tends to be a pronounced increase incontact between the particles and the rotor and stator if the gap issmaller than 0.5 mm, so that much more frictional heat tends to begenerated, which causes toner fusion at the above-mentioned distal end.If the gap is larger than 40 mm, it tends to be impossible to generate aflow with a strong, high-speed stream, making adequate pulverizationunattainable.

This method allows pulverization to be performed simultaneously with theexternal additions, the advantage of which is a shorter manufacturingprocess. Also, the corners of the toner particles are cleanly roundedoff, so that fluidity improves.

If the toner fluidity is low, there tends to be unevenness in solidimage areas, friction chargeability tends to decrease, the amount ofopposite polarity toner tends to increase, toner tends to adherestubbornly to the non-image portions of the photosensitive member andcannot be removed, resulting in base fogging that adversely affects theimage, and transfer efficiency decreases. If the fluidity of the toneris raised by increasing the amount of external added silica, frictioncharging tends to be more uniform, there tends to be less base fogging,image density tends to increase, and the unevenness in solid black imageportions tends to be eliminated. However, this can create problems suchas silica or toner filming on the photosensitive member, or the adhesionof white spots of agglomerated silica to the solid black image portions.

Accordingly, the addition of a small amount of silica yields highfluidity, suppresses the occurrence of suspended silica, and suppressesthe occurrence of silica and toner filming on the intermediate transfermember and the photosensitive member, and silica white spots in thesolid black image portions. This also suppresses the occurrence of theunevenness in solid black image portions that is seen in toners of lowfluidity, results in more uniform transfer, and keeps the occurrence ofopposite polarity toner infrequent, and therefore increases the transferefficiency.

Furthermore, even when transfer is performed at the required pressingforce in places where the toner agglomerates, such as characters andlines, and especially under high temperature and humidity, because ofthe high fluidity of the toner, the toner particles tend not toagglomerate readily, and a sharp image without partial transfer defectscan be obtained.

A working example of the toner pulverization apparatus in thisembodiment shown in FIG. 7 will now be described. A toner to bepulverized 503, which is the portion of a kneaded material that has beencoarsely pulverized and has passed through a mesh with a diameter ofapproximately 1 to 5 mm, is introduced from a metering supply unit 508and is sent to a pulverization supply section by cooling air 511supplied by a cooling unit 509, and this toner is pulverized by apulverizer 500. Raw material 503 is introduced form an inlet 504, and iscarried to the space between a rotor 501, which rotates at a high speedand has a jagged component 506 on its surface, and a stator 502, whichhas a jagged component 507 on its surface and is positioned with anarrow gap between itself and the rotor 501. The raw material particlescollide with each other powerfully and are spherically pulverized in thehigh-speed flow generated between the stator and the rotor that isrotating at a high speed. The particles 510 that have been madespherical come out through a discharge outlet 505 and are sent to acoarse powder grader 513, and these coarse particles are once again sentthrough the inlet 504 by the air 511. The product is sent to a cyclone515 and recovered in a dust trap 520. 512 is a thermometer, 514 is a bagfilter, 516 is an airflow meter, and 517 is a blower. 519 is a vibrator,and 518 is an inorganic micropowder supply apparatus. When the particlesare separated in the coarse powder grading and sent back to thepulverizing section, it is preferable for the inorganic micropowder tobe supplied from the rear. This allows the inorganic micropowder to bemixed more uniformly during collision with the pulverized powder. Anevaporative solvent also can be supplied instead of the inorganicmicropowder.

FIG. 8 is a cross-sectional view along the I-I line in FIG. 7. FIG. 9 isa detail view of the location B in FIG. 8. s1 is the width of theprotrusions of the surface jagged component 507 of the stator 502, s2 isthe distance between the protrusions of the surface jagged component 507of the stator 502, s3 is the height of the protrusions of the surfacejagged component 507 of the stator 502, r1 is the width of theprotrusions of the surface jagged component 506 of the rotor 501, r2 isthe distance between the protrusions of the surface jagged component 506of the rotor 501, and r3 is the height of the protrusions of the surfacejagged component 506 of the rotor 501. The rotor rotates at a highspeed, and in order for the toner to be pulverized efficiently into aspherical shape of small particle size while silica or another inorganicmicropowder is being supplied, the configuration can be such that thedensity of the surface jagged component 507 of the stator 502 is higherthan the density of the jagged component 506 of the rotor 501. It ispreferable for the configuration to be such that there is at least oneprotrusion (and even more preferably, 2.5) per centimeter of peripherallength. It is also preferable if the relationships 0.2≦s1/r1≦0.7 and0.2≦s2/r2≦0.7 are satisfied. In particular, as the powder is beingpulverized while an inorganic micropowder is supplied, since the powderto be pulverized is introduced in a uniformly dispersed state, thedensity must be raised in order to stabilize the collisions with thewall face of the stator. Below 0.2, costs tend to be higher in surfaceprocessing, but over 0.7, the eddy flow tends to be uneven and it isdifficult to pulverize the powder to a small particle size.

(10) Polymerization Method

Emulsion polymerization, suspension polymerization, or the like can beused preferably as the method for producing a toner of small particlesize. With emulsion polymerization, a resin microparticle solutioncontaining an ionic surfactant is prepared, this is mixed with acolorant particle dispersion and a wax release agent particledispersion, and this mixture is agglomerated with an ionic surfactanthaving the opposite polarity from that of the above-mentioned ionicsurfactant, thereby forming toner-based agglomerated particles, afterwhich these are heated to a temperature over the glass transition pointof the resin microparticles so as to fuse the agglomerated particles,and this product is washed and dried to produce a toner. Examples of thesurfactant used here include anionic surfactants based on a sulfate,sulfonate, phosphate, or soap, and cationic surfactants such as aminesalt types and quaternary ammonium salt types. The concurrent use of anonionic surfactant, such as one based on polyethylene glycol, analkylphenol ethylene oxide adduct, or a polyhydric alcohol, is alsoeffective. The means for dispersing these can be a rotary shear type ofhomogenizer, or a dynomill, sand mill, or ball mill having media, or anyother such standard means.

After the particles have been produced, the desired toner can beobtained through a washing step, solid-liquid separation step, anddrying step as needed, but in order to achieve and maintainchargeability, the washing step preferably is carried out by sufficientreplacement washing with ion exchanged water. There are no particularrestrictions on the solid-liquid separation step, but in terms ofproductivity, it is preferable to use absorption filtration, pressurizedfiltration, or the like. Nor are there any particular restrictions onthe drying step, but in terms of productivity, it is preferable to usefreeze drying, flash jet drying, flow drying, vibratory flow drying, orthe like.

With suspension polymerization, a polymerizable monomer, wax, acolorant, and various other additives are uniformly dissolved ordispersed, heated, and uniformly dissolved or dispersed with ahomogenizer, ultrasonic disperser, or the like to produce a monomercomposition, after which this monomer system is dispersed with anordinary stirrer, homomixer, homogenizer, or the like in an aqueousphase of the same temperature as the monomer system and containing adispersion stabilizer.

Preferably, the stirring speed and duration are adjusted so that themonomer liquid drops will be the same size as the required size of thetoner particles. After this, the particle state is maintained by theaction of the dispersion stabilizer, and the system is stirred enoughthat the particles will not settle. The polymerization temperature is atleast 40° C., and is generally set to between 50 and 80° C.

It is preferable here for the stirring speed to be at least 30 m/sec inorder to highly disperse the fixing adjuvant and to obtain small tonerparticles that contain the fixing adjuvant and have a uniform sizedistribution.

Upon completion of the reaction, the toner particles thus produced arewashed, recovered by filtration, and dried. In suspensionpolymerization, it is usually preferable to use water as a dispersionmedium in an amount of 300 to 3000 parts by weight per 100 parts byweight of the monomer system.

All the dispersion media used here can be used by dispersing a suitablestabilizer in an aqueous phase, examples of which include organiccompounds such as polyvinyl alcohol, gelatin, methyl cellulose, methylhydroxypropyl cellulose, ethyl cellulose and carboxymethyl cellulosesodium salt, polyacrylic acid and salts thereof, and starch, andinorganic compounds such as tricalcium phosphate, magnesium phosphate,aluminum phosphate, zinc phosphate, calcium carbonate, magnesiumcarbonate, barium sulfate, calcium sulfate, aluminum hydroxide,magnesium hydroxide, calcium metasilicate, bentonite, silica, andalumina.

Of these dispersion stabilizers, when an inorganic compound is used, theinorganic compound may be produced in an aqueous medium in order toobtain finer particles. For example, in the case of calcium phosphate, asodium phosphate aqueous solution may be mixed with a calcium chlorideaqueous solution under high speed stirring.

Also, in order to achieve a fine dispersion of these stabilizers, asurfactant may be used in an amount of 0.001 to 0.1 parts by weight. Thepurpose of this is to promote the desired action of the above-mentioneddispersion stabilizer, and specific examples thereof include sodiumdodecylbenzene sulfate, sodium tetradecyl sulfate, sodium pentadecylsulfate, sodium octyl sulfate, sodium oleate, sodium laurate, potassiumstearate, and calcium oleate. Azo and diazo polymerization initiatorscan be used as well, such as 2,2′-azobis-(2,4-dimethylvaleronitrile),2,2′-azobisisobutyronitrile, 1,1′-azobis(cyclohexane-1-carbonitrile),2,2′-azobis-4-methoxy-2,4-dimethylvaleronitrile, andazobisisobutyronitrile.

(11) Two-Component Development

An AC bias is applied along with a DC bias between the photosensitivemember and the developing roller. The frequency here is from 5 to 10kHz, the AC bias is from 1.0 to 2.5 kV (p-p), and the peripheral speedratio between the photosensitive member and the developing roller isfrom 1:1.2 to 1:2. More preferably, the frequency here is from 5.5 to 8kHz, the AC bias is from 1.2 to 2.0 kV (p-p), and the peripheral speedratio between the photosensitive member and the developing roller isfrom 1:1.5 to 1:1.8.

Even more preferably, the frequency here is from 5.5 to 7 kHz, the ACbias is from 1.5 to 2.0 kV (p-p), and the peripheral speed ratio betweenthe photosensitive member and the developing roller is from 1:1.6 to1:1.8. When this developing process configuration and the toner of thisembodiment are used, dots can be reproduced faithfully, and thedeveloping gamma characteristic can be made flatter. Both high imagequality and oil-less fixing can be achieved. Also, charge-up under lowhumidity can be prevented even with a high-resistance carrier, allowinghigh image density to be obtained even in continuous use. The reason forthis is believed to be that the combined use of a toner that affordshigh chargeability, this carrier constitution, and an AC bias allowsadhesive strength with the carrier to be reduced, the image density tobe maintained, and fogging to be reduced, and also allows dots to bereproduced faithfully.

If the frequency is less lower 5 kHz, dot reproducibility tends toworsen, and halftone reproducibility also tends to worsen. If thefrequency is higher than 10 kHz, it tends to be impossible to keep up inthe developing region and no further effect tends to be realized. Inthis frequency region, in two-component development using ahigh-resistance carrier, the reciprocal action is at work more betweenthe carrier and the toner than between the developing roller and thephotosensitive member, having the effect of microscopically isolatingthe toner from the carrier, and this affords good dot reproducibilityand halftone reproducibility, and also results in high image density.

If the AC bias is less than 1.0 kV (p-p), there tends to be no effect ofsuppressing charge-up, but fogging tends to increase if the AC bias isgreater than 2.5 kV (p-p). If the peripheral speed ratio between thephotosensitive member and the developing roller is less than 1:1.2 (thatis, if the developing roller is slowed), it tends to be difficult toobtain good image density. If the peripheral speed ratio between thephotosensitive member and the developing roller is greater than 1:2(that is, if the developing roller speeds up), there tends to be moretoner scattering.

(12) Tandem Color Process

In order to form a color image at a high speed, in this embodiment thereare a plurality of toner image forming stations including aphotosensitive member, charging means, and a toner support, theelectrostatic latent image formed on the image support is visualized, aprimary transfer process, in which the toner image produced by thevisualization of the electrostatic latent image is transferred to anendless transfer member by bringing the transfer member into contactwith the image support, is executed sequentially and continuously toform a multilayer transferred toner image on the transfer member, andthen a secondary transfer process, in which the multilayer toner imageformed on the transfer member is transferred all at once to a transfermedium such as paper or an OHP sheet, is executed. In this transferprocess the transfer location is such that d1/v≦0.65 (sec), when d1 (mm)is the distance from a first primary transfer position to a secondprimary transfer position, and v (mm/s) is the peripheral speed of thephotosensitive member. This both makes the machine more compact andaffords higher printing speed. As there has been a recent strong demandfor the machine to be faster and smaller, in order to be capable ofprocessing at least 16 sheets (A4) per minute, and to reduce the size ofthe machine to the point that it can be used in SOHO applications, it isessential that the toner image forming stations be spaced closelytogether and the process speed raised. A constitution in which theabove-mentioned value is 0.65 or less is believed to be the minimum inorder to achieve both this compact size and high printing speed. If thevalue is more than that, the machine becomes larger and the processspeed seems to be slow.

However, when this constitution is employed, for example, after thefirst color of toner (yellow) has undergone primary transfer, the timebefore the second color of toner (magenta) undergoes primary transfer isextremely short, there is virtually no lessening of charge of thetransfer member or lessening of charge of the transferred toner, andwhen the magenta toner is transferred over the yellow toner, the magentatoner is repelled by the charge action of the yellow toner, whichdecreases the transfer efficiency and causes partial transfer defects incharacters. Furthermore, during the primary transfer of the third colorof toner (cyan), the cyan toner is scattered in the course of beingtransferred over the yellow and magenta toner, resulting in pronouncedpartial transfer defects and other such defects during transfer. As thisprocess is repeated, toner of a specific particle size is developedselectively, and there is a considerable difference in the fluidity ofindividual toner particles, they will have differing opportunities forfriction charging, which creates variance in the amount of charge andleads to inferior transfer performance.

In view of this, adopting the toner and developer constitution of thisembodiment results in the uniform dispersion of wax and other internaladditives in the resin, and this stabilizes the charge distribution,suppresses excess charging of the toner, and suppresses fluidityfluctuations, so that a decrease in transfer efficiency and partialtransfer defects of characters during transfer can be prevented withoutsacrificing fixing characteristics.

(13) Cleaner-less Process

This embodiment also can be applied preferably to an electrophotographicapparatus whose basic configuration is a cleaner-less process in whichthe subsequent charging, exposure, and developing processes areperformed without first going through a cleaning process in which tonerremaining on the photosensitive member after the transfer process isrecovered by cleaning.

Using the toner of this embodiment suppresses agglomeration of thetoner, prevents excessive charging, yields stable chargeability, andallows high transfer efficiency to be obtained. It also improves uniformdispersibility in the resin, affords good chargeability, and takesadvantage of the good partability of the material, allowing any tonerremaining on the non-image portions to be recovered well in development.Accordingly, there is no developing memory, in which the previous imagepattern remains in the non-image portions.

(14) Oil-less Color Fixing

This embodiment also can be used preferably in an electrophotographicapparatus equipped with a fixing process designed for oil-less fixing,in which no oil is used in the means for fixing the toner.Electromagnetic inductive heating is preferable as the heating meanshere because it requires a shorter warm-up period and consumes lessenergy. A heating and pressing means is used here that has at least amagnetic field generation means, a rotary heating member comprising atleast a parting layer and a heat generating layer that works byelectromagnetic induction, and a rotary pressing member that forms aconstant nip with the rotary heating member. Transfer paper or anothersuch transfer medium onto which toner has been transferred is passedbetween the rotary heating member and the rotary pressing member to fixthe toner. The rise time during warm-up to the temperature of the rotaryheating member is much shorter than when a conventional halogen lamp isused. Accordingly, the transfer operation begins while the rotarypressing member has yet to be fully heated, so that low temperaturefixing and a wide range of offset resistance are required.

A preferable constitution is to use a fixing belt that separates theheating member and fixing member. A heat-resistant belt such as apolyimide belt or a belt electrocast with nickel that is both heatresistant and deformable can be used preferably as this belt. A siliconerubber, fluororubber, or fluororesin can be used to improve partability.

In the fixing of these, up to now offset has been prevented by coatingwith a parting oil. If a toner that has partability without the use ofan oil is used, then there is no need to coat with a parting oil.However, charging tends to occur if there is no coating with a partingoil, and when an unfixed toner image draws near to the heating member orfixing member, the effect of this charging sometimes causes the toner toscatter. This is particularly likely to occur under low temperature andhumidity.

By using the toner of this embodiment, however, a low temperature fixingand a wide range of offset resistance can be realized without having touse an oil, and color high optical transmissivity can be obtained. Thisalso suppresses excessive charging of the toner, and suppresses tonerscattering caused by the charge effect with the heating member or fixingmember.

WORKING EXAMPLES

The present invention now will be described in further detail throughworking examples, but the present invention is not limited to or bythese examples.

Carrier Manufacturing Example 1

39.7 mol % MnO, 9.9 mol % MgO, 49.6 mol % Fe₂O₃, and 0.8 mol % SrO werepulverized for 10 hours in a wet ball mill, then mixed and dried, afterwhich this mixture was pre-baked by being held at 950° C. for 4 hours.This product was pulverized in the wet ball mill for 24 hours, thengranulated with a spray dryer, dried, and baked by being held at 1270°C. for 6 hours in an electric furnace in an atmosphere of 2% oxygenconcentration. This product was then cracked and graded, which gave acore material made of ferrite particles whose average particle size was50 μm and in which the saturation magnetization was 65 emu/g when amagnetic field of 3000 oersted was applied.

Next, 250 g of a polyorganosiloxane including 15.4 mol % (CH₃)₂SiO unitsexpressed by Chemical Formula 6 below and 84.6 mol % CH₃SiO_(3/2) unitsexpressed by Chemical Formula 7 were reacted with 21 g ofCF₃CH₂CH₂Si(OCH₃)₃, which gave a fluorine-modified silicone resin. Thiswas a demethoxylation reaction by which an organosilicon compoundmolecule containing a perfluoro alkyl group was introduced into thepolyorganosiloxane. In addition, 100 g (calculated as solids) of thisfluorine-modified silicone resin and 10 g of an aminosilane couplingagent (gamma-aminopropyltriethoxysilane) were weighed out and dissolvedin 300 mL of toluene solvent.

where R¹, R², R³, and R⁴ are each a methyl group, and m is 100,representing the average degree of polymerization.

where R¹, R², R³, R⁴, R⁵, and R⁶ are each a methyl group, and n is 80,representing the average degree of polymerization.

Subsequently, 10 kg of the above-described ferrite particles were coatedby stirring them in the above-described coating resin solution for 20minutes using an immersion dry coating equipment. Subsequently, theobtained material was baked at 260° C. for 1 hour, and carrier A1 wasobtained.

Carrier Manufacturing Example 2

A core material was manufactured and coated by the same process as inCarrier Manufacturing Example 1, except that the CF₃CH₂CH₂Si(OCH₃)₃ waschanged to C₈F₁₇CH₂CH₂Si(OCH₃)₃, which gave a carrier A2.

Carrier Manufacturing Example 3

A core material was manufactured and coated by the same process as inCarrier Manufacturing Example 1, except that conductive carbon (EC, madeby Ketjenblack International) was dispersed at a ratio of 5 wt % withrespect to the resin solids by using a ball mill, which gave a carrierA3.

Carrier Manufacturing Example 4

A core material was manufactured and coated by the same process as inCarrier Manufacturing Example 3, except that the added amount ofaminosilane coupling agent was changed to 30 g, which gave a carrier A4.

Carrier Manufacturing Example 5

A core material was manufactured and coated by the same process as inCarrier Manufacturing Example 3, except that the added amount ofaminosilane coupling agent was changed to 50 g, which gave a carrier b1.

Carrier Manufacturing Example 6

A core material was manufactured and coated by the same process as inCarrier Manufacturing Example 1, except that the coating resin waschanged to straight silicone (SR-2411, made by Dow Corning ToraySilicone), which gave a carrier b2.

Carrier Manufacturing Example 7

A core material was manufactured and coated by the same process as inCarrier Manufacturing Example 3, except that the coating resin waschanged to a copolymer of perfluoro-octylethyl acrylate andmethacrylate, which gave a carrier b3.

Carrier Manufacturing Example 8

A core material was manufactured and coated by the same process as inCarrier Manufacturing Example 3, except that the coating resin waschanged to an acrylic-modified silicone resin (KR-9706, made byShin-Etsu Chemical), which gave a carrier b4.

Table 1 shows characteristics of the binder resin of the toner used inthis working example. The resins were a polyester resin whose maincomponent was a bisphenol A propyl oxide adduct, terephthalic acid,trimellitic acid, succinic acid, or fumaric acid, and whose thermalcharacteristics were varied by means of the polymerization conditionsand the mix proportion. This constitution combining a dihydric alcoholwith a dicarboxylic acid or tricarboxylic acid is preferable forachieving good fixability, dispersibility, carrier toner-spentresistance, and pulverization.

TABLE 1 resin PES-1 PES-2 PES-3 PES-4 PES-5 PES-6 pes-7 Mnf (×10⁴) 0.320.52 0.57 0.59 0.32 0.32 0.23 Mwf (×10⁴) 2.10 4.40 5.60 5.91 6.40 10.201.40 Mzf (×10⁴) 26.50 31.00 31.50 40.50 97.50 302.50 7.40 Wmf = Mwf/Mnf6.56 8.46 9.82 10.02 20.00 31.88 6.09 Wzf = Mzf/Mnf 82.81 59.62 55.2668.64 304.69 945.31 32.17 Mpf (×10⁴) 0.62 0.74 0.88 1.02 1.8 2.2 0.5 Tg(° C.) 57.3 57.3 55.0 55.5 58.0 61.0 54.0 Tm (° C.) 107.5 110.8 113.0116.0 121.0 125.0 100.0 Tfb (° C.) 96.2 97.5 98.5 99.2 105.6 107.8 85.0AV (mgKOH/g) 18 15 28 25 15 20 2 Mnf is the number average molecularweight of the binder resin, Mwf is the weight average molecular weightof the binder resin, Mzf is the Z average molecular weight of the binderresin, Wmf is the ratio Mwf/Mnf between the average molecular weight Mwfand the number average molecular weight Wnf, Wzf is the ratio Mzf/Mnfbetween the Z average molecular weight Mzf and the number averagemolecular weight Mnf of the binder resin, Mpf is the peak molecularweight, T_(g) (° C.) is the glass transition point, T_(m) (° C.) is thesoftening point, Tfb (° C.) is the flow beginning temperature, and AV(mgKOH/g) is the resin acid value.

Tables 2, 3, and 4 below list the waxes used in this working example,and the properties thereof. Tw (° C.) is the melting point as measuredby DSC, Ct (%) is the volumetric increase (%) at the melting point+10°C., Ck (wt %) is the heating loss at 220° C., Mnr is the number averagemolecular weight of the wax, Mwr is the weight average molecular weightof the wax, Mzr is the Z average molecular weight of the wax, and “peak”is the peak value of the molecular weight.

TABLE 2 melting volumetric heating point increase loss Ck iodinesaponification wax material Tw (° C.) Ct (%) (wt %) value value WA-1extremely hydrogenated 68 18.5 2.8 2 95.7 jojoba oil WA-2 carnauba wax83 15.3 4.1 10 80 WA-3 extremely hydrogenated 71 3 2.5 2 90 meadowfoamoil WA-4 jojoba oil fatty acid 120 3.5 3.4 2 120 pentaerythritolmonoester WA-5 oleic acid amide 78 0.8 WA-6 ethylene-bis-erucic acid 1051.2 amide WA-7 neopentyl polyol fatty 110 2.2 0.2 150 acid ester WA-8pentaerythritol 125 0.9 0.1 180 tetrastearate (Note) The unit for iodinevalue is iodine g/100 g, and the unit for saponification value ismgKOH/g.

TABLE 3 melting point acid Tw (° C.) value penetration WA-9ethylene/maleic 98 45 1 anhydride/C₃₀ terminal alcohol-typewax/tert-butyl peroxyisopropyl monocarbonate: 100/20/8/4 parts by weightWA-10 propylene/maleic 120 58 1 anhydride/ 1-octanol/dicumyl peroxide:100/15/8/4 parts by weight

TABLE 4 Mnr Mwr Mzr Mwr/Mnr Mzr/Mnr peak WA-1 1009 1072 1118 1.06 1.111.02 × 10³  WA-2 1100 1198 1290 1.09 1.17 1.2 × 10³ WA-3 1015 1078 11241.06 1.11 1.03 × 10³  WA-4 1500 2048 3005 1.37 2.00 3.2 × 10³ WA-5 10001050 1200 1.05 1.20 1.8 × 10³ WA-6 1002 1100 1350 1.10 1.35 1.9 × 10³WA-7 1050 1205 1400 1.15 1.33 2.1 × 10³ WA-8 1100 1980 3050 1.80 2.773.5 × 10³ WA-9 1400 2030 2810 1.45 2.01 2.1 × 10³ WA-10 1400 3250 52002.32 3.71 3.1 × 10³

Table 5 lists the pigments used in this working example.

TABLE 5 material No. composition CM magenta pigment:Pigment Red 57:1 CCcyan pigment:Pigment Blue 15:3 CY yellow pigment:Pigment Yellow 180 BKCarbon Black MA 100S (made by Mitsubishi Chemical)

Table 6 lists the charge control agents used in this working example.

TABLE 6 material No. composition material CA1 Cr metal salt of salicylicacid E-81 (made by Orient derivative Chemical) CA2 K metal salt ofbenzylic acid LR-147 (made by Japan derivative Carlit)

Table 7 lists the additives used in this working example.

TABLE 7 moisture 5 min. particle methanol adsorption ignition drying 5min. 30 min. value/ Inorganic process process size titration amount lossloss value value 30 min. micropowder progenitor material A material B(nm) (%) (wt %) (wt %) (wt %) (μC/g) (μC/g) value S1 silica silicatreated with 6 88 0.1 10.5 0.2 −820 −710 86.59 dimethylpolysiloxane S2silica silica treated with 16 88 0.1 8.5 0.2 −720 −520 72.22dimethylpolysiloxane S3 silica silica treated with 16 88 0.1 5.5 0.2−560 −450 80.36 methylhydrogen polysiloxane S4 silicadimethylpolysiloxane zinc 40 84 0.09 24.5 0.2 −740 −580 78.38 (20)octanoate (1) S5 silica methyl aluminum 40 88 0.1 10.8 0.2 −580 −48082.76 hydrogen distearate polysiloxane (2) (1) S6 silicadimethylpolysiloxane stearic 80 88 0.12 15.8 0.2 −620 −475 76.61 (2)acid amide (1) S7 silica methyl fatty acid 120 89 0.10 6.8 0.2 −580 −48082.76 hydrogen pentaerythritol polysiloxane monoester (1) (1) S8titanium diphenylpolysiloxane stearic 80 88 0.1 18.5 0.2 −750 −650 86.67oxide (10) acid Na(1) S9 barium phenyl palmitic 200 85 0.09 5.5 0.2 −690−540 78.26 titanate hydrogen acid Ca(1) polysiloxane (15) S10 silicasilica treated with 16 68 0.60 1.6 0.2 −800 −620 77.50hexamethyldisilazane

The charge amounts (μC/g) were measured by a friction charging blow-offmethod with a non-coated ferrite carrier. 50 g of carrier and 0.1 g ofsilica or the like were mixed in a 100 mL polyethylene vessel under anatmosphere of 25° C. and 45% RH, the contents were stirred for 5 and 30minutes by vertical rotation at a speed of 100 min⁻¹, after which 0.3 gwas sampled and blown for 1 minute with nitrogen gas at 1.96×10⁴ Pa.

With negative chargeability, it is preferable for the 5 minute value tobe from −100 to −900 μC/g, and for the 30 minute value to be from −50 to−700 μC/g. Silica having a high charge amount can exhibit its functiononly with a small added amount. It is preferable to use silica thatmaintains the amount of charge at the 30 minute value at a level of atleast 40% of the amount of charge at the 5 minute value. If theproportional decrease is large, there is considerable change in theamount of charge during long-term continuous use, and a consistent imagecannot be maintained.

With positive chargeability, it is preferable for the 5 minute value(after 5 minutes of stirring) to be from +100 to +900 μC/g, and for the30 minute value (after 30 minutes of stirring) to be from +50 to +500μC/g. It is preferable to use silica that maintains the amount of chargeat the 30 minute value at a level of at least 40% of the amount ofcharge at the 5 minute value. If the proportional decrease is large,there is considerable change in the amount of charge during long-termcontinuous use, and a consistent image cannot be maintained.

The kneading conditions in this working example are shown in Table 8.

TABLE 8 kneading Trj1 Trk1 Tr2 Rw1 Rw2 Rw1/ conditions (° C.) (° C.) (°C.) (min⁻¹) (min⁻¹) Rw2 Dr1 (A) Dr2 (A) Dr1/Dr2 Q-1 131 61 20 95.0 80.01.2 29.2 12.1 2.4 Q-2 152 40 6 95.0 65.0 1.5 31.0 16.5 1.9 Q-3 118 55 2075.0 65.0 1.2 25.2 12.5 2.0 q-4 100 100 20 60.0 60.0 1.0 19.0 19.0 1.0Trji (° C.) is the heating temperature at the front half of the roll(RL1), Trk1 (° C.) is the heating temperature at the rear half of theroll (RL1), Tr2 (° C.) is the heating or cooling temperature and boththe front and rear portions of the roll (RL2), Rw1 is the rotationalspeed of the roll (RL1), Rw2 is the rotational speed of the roll (RL2),Dr1 is the load current value during rotation of the roll (RL1), and Dr2is the load current value during rotation of the roll (RL2). The amountof raw material introduced was 15 kg/h, the diameter of the rolls RL1and RL2 was 140 mm, and their length was 800 mm.

Tables 9 and 10 list the pulverization conditions in this workingexample.

TABLE 9 supply gap between rotor amount of rotor and peripheral toner tobe cooling air discharge stator speed pulverized temperature sectiontemp. KM1 1.5 mm 130 m/s 5 kg/h 0° C. 45° C. KM2   1 mm 120 m/s 5 kg/h0° C. 40° C.

TABLE 10 supply amount supplied inorganic of toner to be micropowderpulverized KS1 S1 0.48 kg/h KS2 S2 0.12 kg/h KS3 S4 0.09 kg/h KS4 S60.02 kg/h vibrator KS5 S8 0.09 kg/h vibrator KS6  S10 0.02 kg/h KS7vibrator KS8 ethanol spraying

In this working example, pulverization condition KM1 is such that gapbetween rotor and stator: 1.5 mm, rotor peripheral speed: 130 m/s,supplied amount of toner to be pulverized: 5 kg/h, cooling airtemperature: 0° C., and discharge section temperature: 45° C.Pulverization condition KM2 is such that gap between rotor and stator: 1mm, rotor peripheral speed: 120 m/s, supplied amount of toner to bepulverized: 5 kg/h, cooling air temperature: 0° C., and dischargesection temperature: 40° C. s1 was 1 mm, s2 was 4 mm, s3 was 3 mm, r1was 4 mm, r2 was 7 mm, r3 was 3 mm, and the circumference of the statorwas 57 cm. This table shows the inorganic micropowder supplied beforebeing pulverized, its supplied amount, whether or not the inorganicmicropowder was subjected to vibration with a vibrator, and whether ornot the spray treatment was performed.

Table 11 shows the composition and properties of the toners used in thisworking example.

TABLE 11 charge control pulverization pulverization kneading toner resinagent pigment Wax 1 Wax 2 Additive A Additive B conditions 1 conditions2 conditions TM1 PES-1 CA1(3) CM(5) WA1(18) S1(0.5) S4(2.5) KM1 KS1 Q-1TM2 PES-2 CA2(2.5) CM(5) WA2(16) S2(1.5) S5(3.5) KM2 KS2 Q-2 TM3 PES-3CA1(2) + CA3(1.5) CM(5) WA3(12) S3(2.0) S6(2.5) KM1 KS3 Q-3 TM4 PES-4CA2(3) + CA4(2) CM(5) WA4(8) S1(0.5) S7(2.0) KM2 KS6 Q-1 TM5 PES-5CA1(1.5) + CA3(2) CM(5) WA1(5) WA5 S2(1.5) S8(3.5) KM1 KS7 Q-2 (3) TM6PES-6 CA2(3) + CA4(2) CM(5) WA2(6) WA6 S3(2.0) S9(3.5) KM2 KS8 Q-3 (2)Tm7 pes-7 CA4(1) CM(5) PPWAX S10(1.5) km3 q-4 (4) TY1 PES-1 CA1(3) CY(5)WA9(12) S1(0.5) S4(2.5) KM1 KS1 Q-1 TY2 PES-2 CA2(2.5) CY(5) WA10S2(1.5) S5(3.5) KM2 KS3 Q-2 (16) TY3 PES-3 CA1(2) + CA3(1.5) CY(5)WA1(17) S3(2.0) S6(2.5) KM1 KS4 Q-3 TY4 PES-4 CA2(3) + CA4(2) CY(5)WA5(18) S1(0.5) S7(2.0) KM2 KS5 Q-1 TY5 PES-5 CA1(1.5) + CA3(2) CY(5)WA2(5) WA7 S2(1.5) S8(3.5) KM1 KS7 Q-2 (3) TY6 PES-6 CA2(3) + CA4(2)CY(5) WA3(6) WA8 S3(2.0) S9(3.5) KM2 KS8 Q-3 (2) Ty7 pes-7 CA4(1) CY(5)PPWAX S10(1.5) km3 q-4 (4) TC1 PES-1 CA1(3) CC(5) WA9(18) S1(0.5)S4(2.5) KM1 KS1 Q-1 TC2 PES-2 CA2(2.5) CC(5) WA10 S2(1.5) S5(3.5) KM2KS2 Q-2 (16) TC3 PES-3 CA1(2) + CA3(1.5) CC(5) WA2(14) S3(2.0) S6(2.5)KM1 KS3 Q-3 TC4 PES-4 CA2(3) + CA4(2) CC(5) WA7(12) S1(0.5) S7(2.0) KM2KS4 Q-1 TC5 PES-5 CA1(1.5) + CA3(2) CC(5) WA3(5) WA4 S2(1.5) S8(3.5) KM1KS5 Q-2 (3) TC6 PES-6 CA2(3) + CA4(2) CC(5) WA1(6) WA5 S3(2.0) S9(3.5)KM2 KS6 Q-3 (2) Tc7 pes-7 CA4(1) CC(5) PPWAX S10(1.5) km3 q-4 (4) TB1PES-1 CA1(3) BK(5) WA1(18) S1(0.5) S4(2.5) KM1 KS1 Q-1 TB2 PES-2CA2(2.5) BK(5) WA2(16) S2(1.5) S5(3.5) KM2 KS2 Q-2 TB3 PES-3 CA1(2) +CA3(1.5) BK(5) WA3(17) S3(2.0) S6(2.5) KM1 KS4 Q-3 TB4 PES-4 CA2(3) +CA4(2) BK(5) WA8(18) S1(0.5) S7(2.0) KM2 KS5 Q-1 TB5 PES-5 CA1(1.5) +CA3(2) BK(5) WA9(5) WA6 S2(1.5) S8(3.5) KM1 KS6 Q-2 (3) TB6 PES-6CA2(3) + CA4(2) BK(5) WA10(6) WA7 S3(2.0) S9(3.5) KM2 KS7 Q-3 (2) Tb7pes-7 CA4(1) BK(5) PPWAX S10(1.5) km3 q-4 (4)

The blend ratios (in parts by weight) for the pigment, the chargecontrol agent, and the wax per 100 parts by weight of binder resin aregiven in parentheses in Table 11. The blend amounts (in parts by weight)for the additives are indicated per 100 parts by weight of toner matrix.The external addition was performed with an FM20B, using a model Z0S0agitator blade at a rotational speed of 2000 min⁻¹, for a treatment timeof 5 minutes, and at an added amount of 1 kg.

FIG. 1 is a cross-sectional view of the structure of an image formationapparatus for full-color image formation used in this working example.FIG. 1 shows a color electrophotographic printer, with its outer housingremoved. A transfer belt unit 17 comprises a transfer belt 12, a firstcolor (yellow) transfer roller 10Y, a second color (magenta) transferroller 10M, a third color (cyan) transfer roller 10C, a fourth color(black) transfer roller 10K (these rollers are all made from elasticmaterials), a drive roller 11 made from aluminum, a second transferroller 14 made from an elastic material, a second transfer driven roller13, a belt cleaner blade 16 for cleaning away toner remaining on thetransfer belt 12, and a roller 15 located across from the cleaner blade.

The distance from the first color (Y) transfer position to the secondcolor (M) transfer position is 70 mm (this is the same distance from thesecond color (M) transfer position to the third color (C) transferposition, and from the third color (C) transfer position to the fourthcolor (K) transfer position), and the peripheral speed of thephotosensitive member is 125 mm/s. The transfer belt 12 is produced bykneading a conductive filler into an insulating polycarbonate resin, andextruding this mixture in the form of a film. In this working example,the mixture was produced by adding 5 parts by weight conductive carbon(such as ketjen black) to 95 parts by weight polycarbonate resin (suchas Iupilon Z300, made by Mitsubishi Gas Chemical) and then forming afilm from this mixture. The surface was coated with a fluororesin, thethickness of the film was approximately 100 μm, the volumetricresistance was from 10⁷ to 10¹² Ω·cm, and the surface resistance wasfrom 10⁷ to 10¹² ohms per square. The purpose of this was to enhance dotreproducibility, and to effectively prevent the accumulation of chargeand slackness in the transfer belt 12 over extended use. The reason forcoating the surface with a fluororesin was to effectively prevent tonerfilming on the surface of the transfer belt over extended use.Retransfer tends to occur if the volumetric resistance is less than 10⁷Ω·cm, but transfer efficiency tends to drop if the volumetric resistanceis greater than 10¹² Ω·cm.

The first transfer roller is a carbon conductive foamed urethane rollerwith an outside diameter of 10 mm and a resistance of 10² to 10⁶ Ω.During the first transfer operation, the first transfer roller 10 ispressed against a photosensitive member 1 via the transfer belt 12 at apressing force of 1.0 to 9.8 N, and the toner on the photosensitivemember is transferred onto the belt. Retransfer tends to occur if theresistance is less than 10² Ω, but transfer defects tend to occur if 10⁶Ω is exceeded. Transfer defects also tend to occur if the pressing forceis under 1.0 N, but partial transfer defects tend to occur over 9.8 N.

The second transfer roller 14 is a carbon conductive foamed urethaneroller with an outside diameter of 15 mm and a resistance of 10² to 10⁶Ω. The second transfer roller 14 is pressed against the transfer roller13 via the transfer belt 12 and a transfer medium 19, such as a paper oran OHP sheet. This transfer roller 13 is designed to be rotationallydriven by the transfer belt 12. In the second transfer, the secondtransfer roller 14 and the opposing transfer roller 13 are pressedtogether at a pressing force of 5.0 to 21.8 N, and the toner istransferred from the transfer belt onto a recording material 19 such aspaper. Retransfer tends to occur if the resistance is less than 10² Ω,but transfer defects tend to occur if 10⁶ Ω is exceeded. Transferdefects also tend to occur if the pressing force is under 5.0 N, but theload will be too high and jitter tends to occur over 21.8 N.

Four image formation units 18Y, 18M, 18C, and 18K for the various colors(yellow (Y), magenta (M), cyan (C), and black (B)) are disposed in a rowas shown in the drawing.

Aside from the developers contained therein, the image formation units18Y, 18M, 18C, and 18K all have the same constituent members, so thatfor the sake of simplicity, only the image formation unit 18Y used foryellow will be described, and not the other units.

The image formation unit is constituted as follows. 1 is aphotosensitive member, 3 is a pixel laser signal light, 4 is adeveloping roller that is made of aluminum, has an outside diameter of12 mm, and has a magnet with a magnetic force of 1200 gauss. Thisdeveloping roller is located across from the photosensitive member at agap of 0.3 mm, and rotates in the direction indicated by the arrow. 6 isan agitation roller, which agitates the carrier and the toner inside thedeveloping unit and supplies them to the developing roller. The carrierand toner blend ratio is read by magnetic permeability sensor (notshown), and material is supplied as needed from a toner hopper (notshown). 5 is a magnetic blade made of metal, which restricts themagnetic brush layer of the developer on the developing roller. Theamount of developer introduced is 150 g. The gap was set at 0.4 mm.Although not depicted, the power supply applied to the developing roller4 was −500V DC current and 1.5V (p-p) AC current with a frequency of 6kHz. The peripheral speed ratio between the photosensitive member andthe developing roller was set at 1:1.6. The toner and carrier were mixedin a ratio of 93:7, and the amount of developer in the developing unitwas 150 g.

2 is a charging roller made of epichlorohydrin rubber and having anoutside diameter of 12 mm, to which is applied a DC bias of −1.2 kV.This roller charges the surface of the photosensitive member 1 to −600V.8 is a cleaner, 9 is a waste toner box, and 7 is a developer.

The paper conveyance path is formed so that paper 19 is conveyed frombeneath the transfer unit 17, and the paper 19 is sent by a paperconveyance roller (not shown) into a nip where the transfer belt 12 andthe second transfer roller 14 are pressed together.

The toner on the transfer belt 12 is transferred on the paper 19 by the+1000V voltage applied to the second transfer roller 14, and is fixedafter being conveyed to a fixing section made up of a fixing roller 201,a press roller 202, a fixing belt 203, a heating medium roller 204, andan induction heater 205.

FIG. 2 illustrates this fixing process. The belt 203 is stretched aroundthe fixing roller 201 and the heat roller 204. A specific weight isapplied between the fixing roller 201 and the press roller 202, forminga nip between the belt 203 and the press roller 202. The inductionheater 205, which comprises a ferrite core 206 and a coil 207, isprovided on the outer peripheral surface of the heat roller 204, and atemperature sensor 208 is disposed on the outside.

The belt has a 30 μm nickel belt as a base material, over which isprovided a silicone rubber layer of 150 μm, and over this a PFA tube of30 μm. The press roller 202 is pressed against the fixing roller 201 bya pressing spring 209. The recording material 19 with a toner 210 movesalong a guide plate 211. The fixing roller 201 (which serves as thefixing member) comprises an elastic layer 214 having a thickness of 3 mmand composed of silicone rubber with a rubber hardness (according toJIS-A) of 20, provided over the surface of a hollow aluminum roller core213 with a length of 250 mm, an outside diameter of 14 mm, and athickness of 1 mm. A silicone rubber layer 215 is formed over this in athickness of 3 mm, giving an outside diameter of approximately 20 mm.The roller is rotated at 125 mm/s by drive force from a drive motor (notshown). The heat roller 204 has a hollow pipe with an outside diameterof 20 mm and a wall thickness of 1 mm. The fixing belt surfacetemperature was held at 170° C. with a thermistor. The press roller 202serving as the pressing member has a length of 250 mm and an outsidediameter of 20 mm. This roller comprises an elastic layer 217 having athickness of 2 mm and composed of silicone rubber with a rubber hardness(according to JIS-A) of 55, provided over the surface of a hollowaluminum roller core 216 with an outside diameter of 16 mm and athickness of 1 mm. This press roller 202 is rotatably disposed, andforms a nip width of 5.0 mm with the fixing roller 201 when biased by aspring 209 with a spring weight on one side of 147 N.

The operation will now be described. In full-color mode, the firsttransfer rollers 10Y, 10M, 10C, and 10K are all pushed up so as to pressagainst the photosensitive member 1 of the image formation units via thetransfer belt 12. At this point a DC bias of +800V is applied to thefirst transfer rollers. Image signals are sent by laser beams 3 and areincident on the photosensitive members 1 whose surfaces have beencharged by the charging rollers 2, forming electrostatic latent images.The toner on the developing rollers 4 that rotate in contact with thephotosensitive members 1 makes visible the electrostatic latent imagesformed on the photosensitive members 1.

The speed of image formation of the image formation unit 18Y (125 mm/s,which is equal to the peripheral speed of the photosensitive member) andthe moving speed of the transfer belt 12 are set in such a manner thatthe photosensitive member speed is 0.5 to 1.5% slower than the transferbelt speed.

The result of the image formation step is that yellow signal light 3Y isinputted to the image formation unit 18Y, and an image is formed byyellow toner. Simultaneously with this image formation, the yellow tonerimage is transferred from the photosensitive member 1Y to the transferbelt 12 by the action of the first transfer roller 10Y A DC voltage of+800V was applied to the first transfer roller 10Y at this point.

Magenta signal light 3M is inputted to the image formation unit 18M at aspecific timing between the first color (yellow) first transfer andsecond color (magenta) first transfer, an image is formed by magentatoner, and simultaneously with this image formation, the magenta tonerimage is transferred from the photosensitive member 1M to the transferbelt 12 by the action of the first transfer roller 10M. At this pointthe magenta toner is transferred over the first color (yellow) toner.Similarly, images are formed from cyan and black toner, andsimultaneously with this image formation, a YMCK toner image is formedon the transfer belt 12 by the action of the first transfer rollers 10Cand 10K. This is known as a tandem method.

A color image is formed by positionally aligning and superimposing fourcolors of toner image on the transfer belt 12. After the transfer of thelast toner image (black), the four-color toner image is transferred allat once by the action of the second transfer roller 14 onto the paper 19sent from a paper feed cassette (not shown) at a specific timing. Thetransfer roller 13 is grounded at this point, and a DC voltage of +1 kVis applied to the second transfer roller 14. The toner image transferredto the paper is fixed by the pair of fixing rollers 201 and 202. Thepaper then goes through a discharge roller pair (not shown) and isdischarged to the outside of the apparatus. Any toner remaininguntransferred on the intermediate transfer belt 12 is removed by theaction of the cleaner blade 16, so that the belt will be ready for thenext image formation.

Table 12 shows the results of imaging performed by theelectrophotographic apparatus shown in FIG. 1. Table 13 gives evaluationresults of the state of transfer defects in the character portion of afull-color image consisting of three overlapping colors of toner, and ofhow much the paper adheres to the fixing belt during fixing. The chargeamount was measured by a friction charging blow-off method with aferrite carrier. 0.3 g was sampled for durability evaluation, and wasblown for 1 minute with nitrogen gas at 1.96×10⁴ Pa at 25° C. and 45%RH.

TABLE 12 image skipped photosensitive density (ID) overall characterstoner member initial/after solid image during disruption developer tonercarrier filming test fogging uniformity transfer during fixing DM1 TM1A1 no 1.42/1.48 pass pass no none DM2 TM2 A2 no 1.41/1.50 pass pass nonone DM3 TM3 A3 no 1.44/1.48 pass pass no none DM4 TM4 A4 no 1.40/1.48pass pass no none DM5 TM5 A1 no 1.48/1.46 pass pass no none DM6 TM6 A2no 1.41/1.51 pass pass no none dm7 tm7 b1 yes 1.21/1.03 fail fail yestoner scattering DY1 TY1 A1 no 1.49/1.39 pass pass no none DY2 TY2 A2 no1.41/1.38 pass pass no none DY3 TY3 A3 no 1.48/1.45 pass pass no noneDY4 TY4 A4 no 1.41/1.39 pass pass no none DY5 TY5 A1 no 1.47/1.42 passpass no none DY6 TY6 A2 no 1.48/1.44 pass pass no none dy7 Ty7 b2 yes1.28/1.03 fail fail yes toner scattering DC1 TC1 A1 no 1.38/1.42 passpass no none DC2 TC2 A2 no 1.47/1.53 pass pass no none DC3 TC3 A3 no1.46/1.42 pass pass no none DC4 TC4 A4 no 1.47/1.42 pass pass no noneDC5 TC5 A1 no 1.48/1.42 pass pass no none DC6 TC6 A2 no 1.49/1.41 passpass no none dc7 Tc7 b3 yes 1.21/1.02 fail fail yes toner scattering DB1TB1 A1 no 1.45/1.41 pass pass no none DB2 TB2 A2 no 1.42/1.36 pass passno none DB3 TB3 A3 no 1.42/1.41 pass pass no none DB4 TB4 A4 no1.47/1.42 pass pass no none DB5 TB5 A1 no 1.48/1.42 pass pass no noneDB6 TB6 A2 no 1.41/1.37 pass pass no none db7 Tb7 b4 yes 1.24/1.03 failfail yes toner scattering

TABLE 13 second fourth partial adhesion first color color third colorcolor transfer to fixing developer developer developer developerback-transfer defects belt CC1 DY1 DM1 DC1 DB1 no no no CC2 DY2 DM2 DC2DB2 no no no CC3 DY3 DM3 DC3 DB3 no no no CC4 DY4 DM4 DC4 DB4 no no noCC5 DY5 DM5 DC5 DB5 no no no CC6 DY6 DM6 DC6 DB6 no no no cc7 dy7 dm7dc7 db7 yes yes yes

When images were produced using the developers, there was no horizontalline disruption, toner scattering, or partial transfer defects incharacters, the solid black images were uniform, the resulting imageswere of extremely high quality and resolution and were reproduced at 16lines/mm, and high density images having a density of 1.3 or more wereobtained. No base fogging occurred in the non-image portions.Furthermore, when a long-term durability test was conducted with 10,000sheets of A4 paper, there was little change in fluidity and imagedensity, and the characteristics were stable. Uniformity was also goodwhen an overall solid image was formed during development, and nodeveloping memory occurred. There were no streaks in the images incontinuous use. Nor was there any toner-spent onto the carrier. Therewas little change in carrier resistance or decrease in charge amount,and no fogging occurred. There was almost no fluctuation in the chargeamount, whether under high or low temperature and humidity. The partialtransfer defects that occurred during transfer were at a level lowenough to pose no practical problem, and transfer efficiency was about95%. Also, toner filming on the photosensitive member and the transferbelt was low enough to pose no practical problem. The transfer beltcould be cleaned adequately. Almost no toner disruption or tonerscattering occurred during fixing. Further, no transfer defects occurredin full-color images consisting of three overlapping colors, and thepaper did not adhere to the fixing belt during fixing.

However, with the toners tm7, ty7, tc7, tb7 and the developers, skippedcharacters during transfer, partial transfer defects, and back-transferwere more or less at acceptable levels when the process speed was 100mm/s and the photosensitive member gap was 70 mm, but when the processspeed was raised to 125 mm/s, or when the photosensitive member gap waslowered to 60 mm, skipped characters during transfer, partial transferdefects, and back-transfer occurred at levels that were not practicallyacceptable. Fogging and filming of the photosensitive members alsooccurred more often.

Toner-spent on the carrier also occurred more frequently, there wasconsiderable change in carrier resistance, the charge amount decreased,and fogging tended to increase. Also observed were an increase infogging caused by a decrease in charge amount under high temperature andhumidity, and a decrease in image density caused by an increase incharge amount under low temperature and humidity. The transferefficiency dropped to about 60 to 70%. Filming of the transfer belt alsooccurred more often, and cleaning was not performed properly. There wasthinness at the trailing half when an overall solid image was formedduring development. Wax fused to the developing blade during continuoususe, and streaks appeared in the images. The paper adhered to thetransfer belt during the output of images having three overlappingcolors. Toner scattering occurred during fixing.

Table 14 shows the result of an offset resistance test conducted with afixing apparatus featuring a belt not coated with oil, in which a solidimage applied in an amount of at least 1.2 mg/cm² to an OHP sheet wasproduced at a process speed of 100 mm/s. No jamming of the OHP sheetsoccurred in the fixing nip. When an overall solid green image was formedon plain paper, no offset whatsoever occurred up to the 122,000^(th)sheet. No degradation of the belt surface was seen even though it was asilicone or fluorine-based fixing belt not coated with oil.

Optical transmissivity and high-temperature offset resistance wereevaluated. The transmissivity of light of 700 nm was measured with aU-3200 spectrophotometer (Hitachi) at a process speed of 100 mm/s and afixing temperature of 180° C. The table below shows the results forfixability, offset resistance, and preservation stability.

TABLE 14 high-temp. offset preservation OHP transmissivity (%)occurrence temp. (° C.) stability test TM1 89.8 220 pass TM2 90.8 230pass TM3 92.5 230 pass TM4 91.7 230 pass TM5 93.8 220 pass TM6 91.8 230pass tm7 89.8 offset occurred over fail entire temp. range TC1 90.6 220pass TC2 92.8 230 pass TC3 93.5 230 pass TC4 94.5 230 pass TC5 92.8 220pass TC6 93.2 230 pass tc7 88.2 offset occurred over fail entire temp.range

OHP transmissivity was over 80%, and the offset resistance temperaturerange was from 40 to 60° C., meaning that good fixability was exhibitedwith a fixing roller not coated with oil. Almost no agglomeration wasseen in a preservation stability test for 5 hours at 60° C.

The toners tm7 and tc7, on the other hand, caked in the preservationstability test, and its offset resistance temperature range was narrow.

INDUSTRIAL APPLICABILITY

The present invention provides a toner having an additive that includesan inorganic micropowder whose surface is treated with polysiloxane andone or two or more of fatty acids, fatty acid esters, fatty acid amides,and fatty acid metal salts; and a two-component developer in which thetoner is combined with a carrier whose coating resin is afluorine-modified silicone resin containing an aminosilane couplingagent. This makes possible oil-less fixing, in which offset can beprevented while maintaining OHP transmissivity, even without the use ofan oil. This also eliminates toner-spent on the carrier, and extends theservice life of the developer. In addition, partial transfer defects arereduced and high transfer efficiency can be obtained.

1. A toner comprising an additive and a toner matrix that comprises abinder resin, a colorant, and a wax, wherein the additive contains aninorganic micropowder to whose surface polysiloxane and at least oneselected from fatty acids and derivatives thereof are adhered, whereinthe at least one selected from fatty acids and derivatives thereof is atleast one selected from the following groups (1),(2), (3) and (4): (1) agroup of fatty acids consisting of caprylic acid, capric acid, undecylicacid, lauric acid, myristic acid, palmitic acid, stearic acid, behenicacid, montanic acid, lacceric acid, oleic acid, erucic acid, sorbicacid, and linoleic acid; (2) a group of fatty acid esters consisting ofa fatty acid pentaerythritol monoester, a fatty acid pentaerythritoltriester, and a fatty acid trimethylol propane ester; (3) a group ofaliphatic amides consisting of palmitic acid amide, palmitoleic acidamide, stearic acid amide, oleic acid amide, arachidic acid amide,eicosenoic acid amide, behenic acid amide, erucic acid amide, andlignoceric acid amide; and, (4) a group of fatty acid metal saltsconsisting of salts of at least one fatty acid selected from the groupconsisting of caprylic acid, capric acid, undecylic acid, lauric acid,myristic acid, palmitic acid, stearic acid, behenic acid, montanic acid,lacceric acid, oleic acid, erucic acid, sorbic acid, and linoleic acidwith at least one metal selected from the group consisting of aluminum,zinc, calcium, magnesium, lithium, sodium, lead, and barium, and whereinthe inorganic micropowder to whose surface polysiloxane and at least oneselected from fatty acids and derivatives thereof are adhered isobtained by the step of: mixing an inorganic micropowder with a solutionof the polysiloxane and the at least one selected from fatty acids andderivatives thereof dissolved in an organic solvent and then drying theobtained product.
 2. The toner according to claim 1, wherein an averageparticle size of the inorganic micropowder is in a range of 30 nm to 200nm.
 3. The toner according to claim 1, wherein the additive furthercontains a negatively-chargeable silica micropowder whose averageparticle size is in a range of 6 nm to 30 nm.
 4. The toner according toclaim 1, wherein a mixing ratio between (A) the at least one selectedfrom fatty acids and derivatives thereof and (B) the polysiloxane isA:B=2:1 to 1:20.
 5. The toner according to claim 1, wherein thepolysiloxane is at least one selected from dimethylpolysiloxane,diphenyl polysiloxane, methylphenyl polysiloxane, phenyl hydrogenpolysiloxane, methyl hydrogen polysiloxane, and phenyl hydrogen methylhydrogen polysiloxane.
 6. The toner according to claim 1, wherein withrespect to the inorganic micropowder to whose surface polysiloxane andthe at least one selected from fatty acids and derivatives thereof havebeen adhered, an ignition loss is 5 to 25 wt %, when the inorganicmicropowder is ignited at 500° C. for 2 hours.
 7. The toner according toclaim 1, wherein the wax is an ester-based wax with an endothermic peaktemperature (as found by DSC) of 50 to 120° C., an iodine value of 25 orless, a saponification value of 30 to 300, a number average molecularweight (as determined by gel permeation chromatography (GPC)) of 100 to5000, a weight average molecular weight of 200 to 10,000, a ratio of theweight average molecular weight to the number average molecular weight(weight average molecular weight/number average molecular weight) of1.01 to 8, and a ratio of Z average molecular weight to the numberaverage molecular weight (Z average molecular weight/number averagemolecular weight) of 1.02 to 10, and having at least one molecularweight maximum peak in a molecular weight region from 5×10² to 1×10⁴. 8.The toner according to claim 1, wherein the wax is obtained by reactinga C₄ to C₃₀ long chain alkyl alcohol, an unsaturated polycarboxylic acidor anhydride thereof, and a hydrocarbon wax, has a molecular weightdistribution (as determined by GPC) such that a weight average molecularweight is from 1000 to 6000, a Z average molecular weight is from 1500to 9000, a ratio of the weight average molecular weight to numberaverage molecular weight (weight average molecular weight/number averagemolecular weight) is from 1.1 to 3.8, a ratio of the Z average molecularweight to the number average molecular weight (Z average molecularweight/number average molecular weight) is from 1.5 to 6.5, and there isat least one molecular weight maximum peak in a region from 1×10³ to3×10⁴, and the presence of an endothermic peak temperature (as found byDSC) of from 80° C. to 120° C., and an acid value of from 5 to 80mgKOH/g.
 9. The toner according to claim 1, wherein the wax is at leastone wax selected from a wax based on an aliphatic amide having at least16 to 24 carbon atoms, and a wax based on an alkylenebis fatty acidamide of a saturated or a mono- or diunsaturated fatty acid.
 10. Thetoner according to claim 1, wherein the wax is at least one wax selectedfrom the group consisting of hydroxystearic acid derivatives, glycerolfatty acid esters, glycol fatty acid esters, and sorbitan fatty acidesters.
 11. A toner comprising an additive and a toner matrix thatcomprises a binder resin, a colorant, and a wax, wherein the additivecontains an inorganic micropowder to whose surface polysiloxane and atleast one selected from fatty acids and derivatives thereof are adhered,wherein the at least one selected from fatty acids and derivativesthereof is at least one selected from the following groups (1), (2), (3)and (4): (1) a group of fatty acids consisting of caprylic acid, capricacid, undecylic acid, lauric acid, myristic acid, palmitic acid, stearicacid, behenic acid, montanic acid, lacceric acid, oleic acid, erucicacid, sorbic acid, and linoleic acid; (2) a group of fatty acid estersconsisting of a fatty acid pentaerythritol monoester, a fatty acidpentaerythritol triester, and a fatty acid trimethylol propane ester;(3) a group of aliphatic amides consisting of palmitic acid amide,palmitoleic acid amide, stearic acid amide, oleic acid amide, arachidicacid amide, eicosenoic acid amide, behenic acid amide, erucic acidamide, and lignoceric acid amide; and (4) a group of fatty acid metalsalts consisting of salts of at least one fatty acid selected from thegroup consisting of caprylic acid, capric acid, undecylic acid, lauricacid, myristic acid, palmitic acid, stearic acid, behenic acid, montanicacid, lacceric acid, oleic acid, erucic acid, sorbic acid, and linoleicacid with at least one metal selected from the group consisting ofaluminum, zinc, calcium, magnesium, lithium, sodium, lead, and andbarium, and wherein the inorganic micropowder to whose surfacepolysiloxane and at least one selected from fatty acids and derivativesthereof are adhered is obtained by the steps of: mixing an inorganicmicropowder with a solution of polysiloxane dissolved in an organicsolvent, mixing the polysiloxane-treated inorganic micropowder with asolution of the at least one selected from fatty acids and derivativesthereof dissolved in an organic solvent, and then drying the obtainedproduct.
 12. A toner comprising an additive and a toner matrix thatcomprises a binder resin, a colorant, and a wax, wherein the additivecontains an inorganic micropowder to whose surface polysiloxane and atleast one selected from fatty acids and derivatives thereof are adhered,wherein the at least one selected from fatty acids and derivativesthereof is at least one selected from the following groups (1), (2), (3)and (4): (1) a group of fatty acids consisting of caprylic acid, capricacid, undecylic acid, laurie acid, myristic acid, palmitic acid, stearicacid, behenic acid, montanic acid, lacceric acid, oleic acid, erucicacid, sorbic acid, and linoleic acid; (2) a group of fatty acid estersconsisting of a fatty acid pentaerythritol monoester, a fatty acidpentaerythritol triester, and a fatty acid trimethylol propane ester;(3) a group of aliphatic amides consisting of palmitic acid amide,palmitoleic acid amide, stearic acid amide, oleic acid amide, arachidicacid amide, eicosenoic acid amide, behenic acid amide, erucic acidamide, and lignoceric acid amide; and (4) a group of fatty acid metalsalts consisting of salts of at least one fatty acid selected from thegroup consisting of caprylic acid, capric acid, undecylic acid, lauricacid, myristic acid, palmitic acid, stearic acid, behenic acid, montanicacid, lacceric acid, oleic acid, erucic acid, sorbic acid, and linoleicacid with at least one metal selected from the group consisting ofaluminum, zinc, calcium, magnesium, lithium, sodium, lead, and barium,and wherein the inorganic micropowder to whose surface polysiloxane andat least one selected from fatty acids and derivatives thereof areadhered is obtained by the steps of: mixing an inorganic micropowderwith a solution of at least one of a coupling agent, polysiloxane, and amixture thereof dissolved in an organic solvent, mixing the at least oneof the coupling agent-, the polysiloxane-, or the mixturethereof-treated inorganic micropowder with a solution of thepolysiloxane and the at least one selected from fatty acids andderivatives thereof in an organic solvent, and then drying the obtainedproduct.
 13. A two-component developer comprising, a toner comprising anadditive and a toner matrix that comprises at least a binder resin, acolorant, and a wax, and a carrier, wherein the additive contains aninorganic micropowder to whose surface polysiloxane and at least oneselected from fatty acids and derivatives thereof are adhered, whereinthe at least one selected from fatty acids and derivatives thereof is atleast one selected from the following groups (1), (2), (3) and (4): (1)a group of fatty acids consisting of caprylic acid, capric acid,undecylic acid, lauric acid, myristic acid, palmitic acid, stearic acid,behenic acid, montanic acid, lacceric acid, oleic acid, erucic acid,sorbic acid, and linoleic acid; (2) a group of fatty acid estersconsisting of a fatty acid pentaerythritol monoester, a fatty acidpentaerythritol triester, and a fatty acid trimethylol propane ester;(3) a group of aliphatic amides consisting of palmitic acid amide,palmitoleic acid amide, stearic acid amide, oleic acid amide, arachidicacid amide, eicosenoic acid amide, behenic acid amide, erucic acidamide, and lignoceric acid amide; and (4) a group of fatty acid metalsalts consisting of salts of at least one fatty acid selected from thegroup consisting of caprylic acid, capric acid, undecylic acid, lauricacid, myristic acid, palmitic acid, stearic acid, behenic acid, montanicacid, lacceric acid, oleic acid, erucic acid, sorbic acid, and linoleicacid with at least one metal selected from the group consisting ofaluminum, zinc, calcium, magnesium, lithium, sodium, lead, and barium,wherein the carrier comprises a core material whose surface is coatedwith a resin containing a fluorine-modified silicone resin containing anaminosilane coupling agent, and wherein the inorganic micropowder towhose surface polysiloxane and at least one selected from fatty acidsand derivatives thereof are adhered is obtained by the step of: mixingan inorganic micropowder with a solution of the polysiloxane and the atleast one selected from fatty acids and derivatives thereof dissolved inan organic solvent and then drying the obtained product.
 14. Thetwo-component developer according to claim 13, wherein an averageparticle size of the inorganic micropowder is in a range of 30 nm to 200nm.
 15. The two-component developer according to claim 13, wherein theadditive further contains a negatively-chargeable silica micropowderwhose average particle size is in a range of 6 nm to 30 nm.
 16. Thetwo-component developer according to claim 13, wherein a mixing ratiobetween (A) the at least one selected from fatty acids and derivativesthereof and (B) the polysiloxane is A:B=2:1 to 1:20.
 17. Thetwo-component developer according to claim 13, wherein the polysiloxaneis at least one selected from dimethylpolysiloxane, diphenylpolysiloxane, methylphenyl polysiloxane, phenyl hydrogen polysiloxane,methyl hydrogen polysiloxane, and phenyl hydrogen methyl hydrogenpolysiloxane.
 18. The two-component developer according to claim 13,wherein with respect to the inorganic micropowder to whose surfacepolysiloxane and the at least one selected from fatty acids andderivatives thereof have been adhered an ignition loss is 5 to 25 wt %,when the inorganic micropowder is ignited at 500° C. for 2 hours. 19.The two-component developer according to claim 13, wherein the wax is anester-based wax with an endothermic peak temperature (as found by DSC)of 50 to 120° C., an iodine value of 25 or less, a saponification valueof 30 to 300, a number average molecular weight (as determined by gelpermeation chromatography (GPC)) of 100 to 5000, a weight averagemolecular weight of 200 to 10,000, a ratio of the weight averagemolecular weight to the number average molecular weight (weight averagemolecular weight/number average molecular weight) of 1.01 to 8, and aratio of Z average molecular weight to the number average molecularweight (Z average molecular weight/number average molecular weight) of1.02 to 10, and the presence of at least one molecular weight maximumpeak in a molecular weight region from 5×10² to 1×10⁴.
 20. Thetwo-component developer according to claim 13, wherein the wax isobtained by reacting a C₄ to C₃₀ long chain alkyl alcohol, anunsaturated polycarboxylic acid or anhydride thereof, and a hydrocarbonwax, has a molecular weight distribution (as determined by GPC) suchthat a weight average molecular weight is from 1000 to 6000, a Z averagemolecular weight is from 1500 to 9000, a ratio of the weight averagemolecular weight to number average molecular weight (weight averagemolecular weight/number average molecular weight) is from 1.1 to 3.8, aratio of the Z average molecular weight to the number average molecularweight (Z average molecular weight/number average molecular weight) isfrom 1.5 to 6.5, and the presence of at least one molecular weightmaximum peak in a region from 1×10³ to 3×10⁴, and has an endothermicpeak temperature (as found by DSC) of from 80° C. to 120° C. and an acidvalue of from 5 to 80 mgKOH/g.
 21. The two-component developer accordingto claim 13, wherein the wax is at least one wax selected from a waxbased on an aliphatic amide having at least 16 to 24 carbon atoms, and awax based on an alkylenebis fatty acid amide of a saturated or a mono-or diunsaturated fatty acid.
 22. The two-component developer accordingto claim 13, wherein the wax is at least one wax selected from the groupconsisting of hydroxystearic acid derivatives, glycerol fatty acidesters, glycol fatty acid esters, and sorbitan fatty acid esters. 23.The two-component developer according to claim 13, wherein the coatingresin of the carrier contains the aminosilane coupling agent in aproportion of 5 to 40 parts by weight per 100 parts by weight of thecoating resin.
 24. The two-component developer according to claim 13,wherein the coating resin of the carrier contains a conductivemicropowder in a proportion of 1 to 15 parts by weight per 100 parts byweight of the coating resin.
 25. A two-component developer comprising, atoner comprising an additive and a toner matrix that comprises at leasta binder resin, a colorant, and a wax, and a carrier, wherein theadditive contains an inorganic micropowder to whose surface polysiloxaneand at least one selected from fatty acids and derivatives thereof areadhered, wherein the at least one selected from fatty acids andderivatives thereof is at least one selected from the following groups(1), (2), (3) and (4): (1) a group of fatty acids consisting of caprylicacid, capric acid, undecylic acid, lauric acid, myristic acid, palmiticacid, stearic acid, behenic acid, montanic acid, lacceric acid, oleicacid, erucic acid, sorbic acid, and linoleic acid; (2) a group of fattyacid esters consisting of a fatty acid pentaerythritol monoester, afatty acid pentaerythritol triester, and a fatty acid trimethylolpropane ester; (3) a group of aliphatic amides consisting of palmiticacid amide, palmitoleic acid amide, stearic acid amide, oleic acidamide, arachidic acid amide, eicosenoic acid amide, behenic acid amide,erucic acid amide, and lignoceric acid amide; and (4) a group of fattyacid metal salts consisting of salts of at least one fatty acid selectedfrom the group consisting of caprylic acid, capric acid, undecylic acid,lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid,montanic acid, lacceric acid, oleic acid, erucic acid, sorbic acid, andlinoleic acid with at least one metal selected from the group consistingof aluminum, zinc, calcium, magnesium, lithium, sodium, lead, andbarium, wherein the carrier comprises a core material whose surface iscoated with a resin containing a fluorine-modified silicone resincontaining an aminosilane coupling agent, and wherein the inorganicmicropowder to whose surface polysiloxane and at least one selected fromfatty acids and derivatives thereof are adhered is obtained by the stepsof: mixing an inorganic micropowder with a solution of polysiloxanedissolved in an organic solvent, mixing the polysiloxane-treatedinorganic micropowder with a solution of the at least one selected fromfatty acids and derivatives thereof dissolved in an organic solvent, andthen drying the obtained product.
 26. A two-component developercomprising, a toner comprising an additive and a toner matrix thatcomprises at least a binder resin, a colorant, and a wax, and a carrier,wherein the additive contains an inorganic micropowder to whose surfacepolysiloxane and at least one selected from fatty acids and derivativesthereof are adhered, wherein the at least one selected from fatty acidsand derivatives thereof is at least one selected from the followinggroups (1), (2), (3) and (4): (1) a group of fatty acids consisting ofcaprylic acid, capric acid, undecylic acid, lauric acid, myristic acid,palmitic acid, stearic acid, behenic acid, montanic acid, lacceric acid,oleic acid, erucic acid, sorbic acid, and linoleic acid; (2) a group offatty acid esters consisting of a fatty acid pentaerythritol monoester,a fatty acid pentaerythritol triester, and a fatty acid trimethylolpropane ester; (3) a group of aliphatic amides consisting of palmiticacid amide, palmitoleic acid amide, stearic acid amide, oleic acidamide, arachidic acid amide, eicosenoic acid amide, behenic acid amide,erucic acid amide, and lignoceric acid amide; and (4) a group of fattyacid metal salts consisting of salts of at least one fatty acid selectedfrom the group consisting of caprylic acid, capric acid, undecylic acid,lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid,montanic acid, lacceric acid, oleic acid, erucic acid, sorbic acid, andlinoleic acid with at least one metal selected from the group consistingof aluminum, zinc, calcium, magnesium, lithium, sodium, lead, andbarium, wherein the carrier comprises a core material whose surface iscoated with a resin containing a fluorine-modified silicone resincontaining an aminosilane coupling agent, and wherein the inorganicmicropowder to whose surface polysiloxane and at least one selected fromfatty acids and derivatives thereof are adhered is obtained by the stepsof: mixing an inorganic micropowder with a solution of at least one of acoupling agent, polysiloxane, or a mixture thereof dissolved in anorganic solvent, mixing the at least one of the coupling agent-, thepolysiloxane-, or the mixture thereof-treated inorganic micropowder witha solution of the polysiloxane and the at least one selected from fattyacids and derivatives thereof in an organic solvent, and then drying theobtained product.